By the age of 20, Eliza Scanlen had already played a full American anthology of roles, from dark and depraved (Amy Adams’s rollerskating, psychopathic kid sister on HBO’s Sharp Objects), to sinister (Mayella, who falsely accuses a black man of rape, in Aaron Sorkin’s Broadway staging of To Kill A Mockingbird) to literary heroine (Beth, the docile yet dogged, sickly sister in Greta Gerwig’s Little Women).

And yet the Australian actor, now 21, who started out playing a stalker on Home and Away, hadn’t played the staple of rising star roles: a character who’s fallen in love.

“That’s obviously something that every actor wants to do,” Scanlen tells me by phone from her home in Sydney. But, in keeping with a burgeoning career already distinguished for its challenging, ferocious roles, such romance came with an edge. Enter Babyteeth, an Australian film from director Shannon Murphy, in which Scanlen plays Milla, a terminally ill teen who falls for Moses (Toby Wallace), a restless, rat-tailed, 23-year-old vagabond she meets at a train station.

The film once again finds Scanlen channeling a character of striking dualities – a girl forced to be more circumspect than her baffled, grieving parents (Essie Davis and Ben Mendelsohn), fierce yet naive – in a brazen, playful performance. “A coming-of-age story has never felt so free to me,” she says, and different from the many scripts she’s read, “because it was Australian – I can’t put my finger on why. I think it’s this really dark unsentimental humor that [screenwriter] Rita [Kalnejais] nails.”

Since her breakout role in Sharp Objects just two summers ago, Scanlen has rapidly built a résumé of rangy, captivating performances. Her acting often teeters delicately between unhinged and deeply grounded, able to strike a tricky balance between poles – as Milla, a reverent, unpredictable teen staring down a bitter diagnosis, for example, or as Amma Crellin in Sharp Objects, the beguiling, rollerskating (spoiler alert) killer at turns sweet, saucy and terrifying.

On screen, Scanlen is unafraid to hold the center against such commanding actors as Sharp Objects’ Adams and Patricia Clarkson, Little Women’s Laura Dern.

That fearlessness contrasts with how she describes the first year of her Hollywood career. “I think before I did Little Women, I was still quite afraid – I didn’t want to take up space,” she says. Scanlen booked Sharp Objects, with an audition Adams said “floored” director Jean-Marc Vallee, just weeks after graduating high school in Sydney and, at 18, moved to Los Angeles. The high-octane six months of filming and then promoting the series, far from her family and isolated in a new country, was “an incredibly scary experience for me”, Scanlen says. Her role as Amma was “emotionally turbulent, and I just didn’t really know what to do with that experience, because I didn’t know anyone my age who had that experience. There was no one to talk to about it.”

So to arrive at the convivial Little Women set in Boston in summer 2018 – the March sisters shared an apartment in the city – and “to meet Emma [Watson] and Florence [Pugh] and Saoirse [Ronan], who had all experienced the same thing that I did. I learned a lot from watching them,” she says.

Given the still rampant gender inequity and underrepresentation of female directors, Scanlen’s Hollywood career has been remarkably full of projects led by women — Sharp Objects, based on Gillian Flynn’s novel and created by Marti Noxon, Gerwig’s Little Women, and now Murphy’s Babyteeth. It’s unusual, Scanlen says, but still, she feels “lucky to have been thrust into the industry at a time like this, where women are being given the autonomy that they’ve always deserved and what the industry has needed for so long.”

To observe so many women in creative roles – writers, producers, directors, lead actors – has “imbued in me a confidence, a sense that I should be here, and that I deserve to be here. And if I want to try another creative role in the industry, then I can do it and there is nothing holding me back.”

Working with Gerwig and Murphy in particular inspired her to plunge ahead with last year’s Mukbang, a short film she wrote, directed and casted with friends, on a teenage girl’s wire-crossing, world-opening foray into the niche internet corner of Korean “mukbang” videos in which creators eat large quantities of food on webcams.

It’s also bolstered the confidence to call out double standards; in December 2019, while promoting Little Women, Scanlen declared to the Independent that she was “tired of making excuses for young male actors by saying that they’re just boys and they’ll get over it. The ‘boys will be boys’ thing, I think that’s really the crux of it. Everyone should know what it means to be professional.”

She laughs at my mention of the comments now, having not expected them to generate a headline, but stood by them. The different standards of professionalism is, she says, something she’s experienced on sets. “I think women in key creative roles – and I guess it’s because they haven’t had that opportunity at their fingertips their whole lives, it hasn’t always been available to them – they are more aware of the responsibility that it holds.”

Men have been in said positions for longer, “and it comes with a complacency and just maybe a self-righteousness I really despise”. There are “a lot of men I’ve worked with that are great”, she notes, “but it’s sad that it only takes a few to be angry about it”.

In moments such as these and the film industry at large, Scanlen relies less on direct advice from her veteran co-workers than a model of how to conduct a career. Working with such veteran actors as Clarkson, Adams and Ronan instilled in her “a sense of confidence and ability to tackle situations like that when they come”, she says. Ronan, in particular, “takes up space in a way that is not overbearing – it’s really inclusive”.

Scanlen will next appear in another twisted role, alongside Tom Holland and Robert Pattinson in gothic thriller The Devil All The Time, to premiere on Netflix at a yet unannounced date, and later in M Night Shyamalan’s latest, still-untitled project for Universal. Beyond that, Scanlen says she’s currently “sick of seeing the female plot device that people like to say is the heart of the film, but most definitely is not”, and instead on the lookout for the mundane, frenetic, idiosyncratic.

“I want to see more of female characters identifying less with the struggle of the patriarchy and more just normalizing confident, empowered women,” she says, “rather than having the patriarchy or gender roles or the limitations or restrictions that have been placed on women defining the story.”

Bringing more women to the lead of creative projects, both in front of and behind the camera, is “an important movement within our industry”, she added, “but I’m looking forward to the day that women can lead a film or a TV show and for that to not be the selling point.”

• Babyteeth is out in the US now and in the UK on 21 August