She’s in summer’s most controversial TV show and is part of a new wave of trans actors and models carving out careers on their own terms. This is her first big UK interview.

“Did you see last night’s episode of Euphoria?” In juice bars and nail salons, Uber rides and yoga classes, it’s all anyone in Los Angeles is talking about. Tonight, American audiences will be watching the final episode of HBO’s controversial eight-part drama, which charts the drug-addled sex lives of a group of high-school teenagers with unflinching honesty (and approximately 423 close-up shots of penises). Since its US premiere in June, Euphoria has become a monster hit, racking up millions of views and downloads and becoming the main topic of water-cooler conversation. In LA, where the show was filmed, giant billboards of its lead, the former Disney actress Zendaya, loom from the sides of buildings. But while Zendaya’s portrayal of troubled teen Rue might be the reason people started watching the show, it’s the newcomer Hunter Schafer’s heart-wrenching depiction of transgender Jules that keeps them coming back.

When you see the 20-year-old Schafer starring in graphically intimate scenes portrayed with nuance and emotion, it’s hard to believe this is her first acting gig. She has spent the past two years on the fashion scene, breaking barriers to become one of the first trans models to walk for the likes of Dior, Marc Jacobs and Miu Miu. When we meet for oat milk cappuccinos in Beverly Hills, I expect a flurry of fans to run up and demand selfies with her, but Schafer’s profile is mostly under the radar — for now.

“I’ve only just started to get recognised,” she says. “I went for a walk the other day and this guy in his truck rolled down the window and was like, ‘Yo, I love your show!’ It’s the strangest thing.” Said show has divided American critics, with some praising it for its bravery and hyper-stylised beauty, while others dismiss it as needlessly shocking and provocative, yet its success is uncontestable: HBO has commissioned a second series and, over here, Sky Atlantic has rescheduled it from autumn to start this week.

How does overnight success feel? “I’ve had a few offers off the back of it, which has been cool,” she says. “But I’m just trying to take it slow, because it’s a lot of change and it’s happening really fast. I just don’t want to go insane.” Schafer is disarmingly sweet and sensitive in person, smiling goofily when talking about something she loves, fiddling with a strand of her pale blonde hair when facing a question she’s not sure how to answer. She admits she found the audition process for the show “intimidating”, especially after she learnt that her first scenes would include portrayals of violent, abusive sex with a much older man and cutting herself. “It was quite the first impression of the show,” she says with a wry smile. “And, yeah, I was a little concerned. But then I got the scripts for the rest of the episodes and that’s when it clicked for me that, wow, this would actually be a really cool thing to be a part of. I like where this story is going.”

While many of the scenes are extreme in nature, Schafer insists she never felt uncomfortable on set and says there was nothing she refused to do, except take her bra off during a sex scene. “I trusted Sam [Levinson, the show’s creator] from the get-go and I trusted the vision. And if there was an instance when I wanted to say no to something, we had the intimacy co-ordinator there and I had a trans co-ordinator. That support made me even more willing to go to places that I might not be comfortable with.” The show’s trans co-ordinator, Scott (a fellow trans person), was on set for Schafer to consult whenever there were scenes focused around her trans identity; she has said that he was a vital support to her on an otherwise cisgender set. But her biggest encouragement came from her castmates, whom she grew extremely close to during filming — particularly Zendaya, whom Schafer refers to as Zee: “We were actually hanging out last night, just chilling on her sofa.”

Schafer grew up in a quiet suburb of Raleigh in North Carolina. She is the oldest of four siblings. Her father is a pastor and her mother also works in the ministry. She’s diplomatic when I ask her what it was like growing up in that environment. “It’s not my favourite place in the world. It’s in the Bible Belt, and it’s normal to be backwards there. I was living there when they passed House Bill 2, which excluded trans people from public bathrooms. Growing up as a young trans person and having your own legislature telling you that you don’t exist, or that you’re a danger to society, that sucks.”

She started to transition when she was 14, and kept it a secret from her family at first. “I would get mascara from my friends and put it on in the bathroom at school and then take it off before I got picked up. I bought a pair of $20 heels from Sears and would sneak them into my backpack to wear at school. My close friends knew, but a lot of people in my community didn’t.” She describes her experience of transitioning as a slow, drawn-out process. “A lot of it was in a stationary moment, waiting, trying to figure things out. Then I got approved by a therapist to start hormones.” She was still in high school at the time, so how did her parents react when she told them? Schafer squirms in her seat. “I don’t know if I want to get into that.” She stresses that her parents are supportive now. “I presented more androgynously in high school, when my parents and I started becoming more on the same page with being trans. At that point in our lives, none of us knew what being trans was. We had to YouTube Jazz Jennings and Laverne Cox. That’s all I had. They have come such a long way from where we were at that point.”

It was in Raleigh that she was discovered by a photographer, who put her in touch with her current agents. At 18 she moved to New York and quickly fell in with the fashion set, interning for the irreverent “anti-fashion” label Vaquera. She hadn’t considered acting until she spotted Euphoria’s open casting call on Instagram; a few days later she got the call, via her agent, to come to an audition. She moved to LA in October, when filming started, and currently lives on her own in Silver Lake, though she doesn’t feel settled yet. “We started filming before I could really settle in, so I don’t have a couch, I don’t have a TV — it’s literally a bed and a desk,” she says. “Now I want to start again so that by season two it feels like a proper home.”

Schafer got to relive her high-school years in Euphoria. “It was therapeutic in a lot of ways,” she says, “and fun, because I got to be in high school again and feel more like myself than I ever did in my real life, and looking the way I wanted to.” She was closely involved with creating her character’s wardrobe, which consists of a succession of tiny miniskirts, fluffy backpacks and glittery neon make-up. “If I was 17, that is exactly what I would be wearing,” she says. The day we meet there’s more than a touch of Jules to her outfit — a multicoloured, oversized Versus Versace T-shirt worn as a dress and a pair of chunky black Dr Martens that make her long legs look even more Bambi-like.

She struggles with the idea of being a poster girl for the trans movement, or even an activist, yet she has been outspoken in the past about trans rights, particularly in relation to House Bill 2, which she speaks about to her more than 300,000 Instagram followers. “I feel way too young to be a role model,” she says. “I still have a lot of messiness to get out of my system. I’m 20! Trans people have come up to me and shown me pictures of their pre-transition selves, sharing these moments with me that felt really private and personal. That’s been very affirming. But it’s frustrating because I will talk about being a trans person, which is a normal, everyday part of my life, and merely being vocal about it will have cis people thinking I’m an activist — just because I talk about who I am. Being an activist has never been my goal. My goal has always been to be an artist.” She still comes across prejudice, particularly on social media. “There’s been a lot of discourse about my anatomy, which is dumb.” When I ask how she feels about Donald Trump, she splutters into laughter. I’m guessing she’s not a fan? “No! F*** Trump. F*** the administration.”

Schafer says she’s no longer interested in modelling: “It’s safe to say I was only modelling because I needed to pay the bills, but I loved the fashion industry.” She had a place to study fashion at Central St Martins, but gave it up for the part in Euphoria. “Acting feels a lot more fulfilling right now,” she says. There were some high points during her fashion career, though, like walking for Miu Miu alongside Naomi Campbell, Gwendoline Christie and Chloë Sevigny: “That was an insane cast. We were all lined up in this hallway waiting to walk and I couldn’t speak. I was sweating so hard — it was unreal.” Now her downtime is spent drawing in coffee shops or dancing. “I used to do contemporary dance and I love improvisation — it’s my favourite way to have a conversation with somebody.” Is she dating at the moment? More squirming. “It’s complicated,” she says with a laugh. “I look at someone like FKA Twigs, who’s learning how to sword fight, do ballet, pole dance, and also being a musician — that’s goals. That’s what I’m working towards. I want to give everything a shot.”