Skin was the unassuming star of Euphoria season two. Fans applauded the characters' visible acne throughout the episodes and trending skincare products and tools even played a key role in Sydney Sweeney's character, Cassie Howard's, plot line.

In fact, Cassie's extensive 4 a.m. skincare routine was actually made up of products from the actress' own medicine cabinet. "During quarantine, I started experimenting along with different facial tools and watching a lot of different videos, so I just bought all of these products and had a bin of them," Sweeney tells InStyle. "So when Sam [Levinson] was talking to me about what we were going to do in the scene, he said, 'Yeah, I think you'll just like wash your face and we'll try different things.' And I said, 'I might have some stuff we can try and play around with.'"

Sweeney says when filming that scene, she "dug into that manic feeling of wanting to be perfect for somebody else and not yourself and that fear of aging, that fear of not being beautiful and just thinking that you have to do all of these things on the outside to impress others, when truly it's all on the inside."

Sure, Cassie's routine was a hyperbolic version of what'd you see on #SkinTok and is not recommended to be repeated at home, but based on Sweeney's product selection, it's evident she knows a thing or two about skincare. So Laneige has tapped the actress as its first-ever celebrity brand ambassador.

Naturally, she's familiar with the K-beauty brand's products – specifically the cult-favorite Lip Sleeping Mask. "I've been a fan of the Laneige Lip Sleeping Mask for quite some time now and when I started using that, I figured I should try some of their other products because I started following them and I saw that they had skincare," Sweeney shares. "So I started using the rest of their skincare and my skin got so clear and soft. Everyone started noticing – even Donni Davey [Euphoria's head makeup artist] asked me what I was doing different to my skin. And I got everyone addicted."

Sweeney is kicking off her new gig by starring in the campaign for Laneige's upgraded Water Bank Collection, featuring hero ingredient, Blue Hyaluronic Acid. This form of HA is fermented with a moisturizing agent derived from deep sea algae in order to shrink its molecular size to better penetrate the skin. According to the brand, its Blue Hyaluronic Acid is 2000 times smaller than the HA in the original Water Bank products.

The updated collection lineup includes the Water Bank Blue Hyaluronic Cream Moisturizer ($40), Water Bank Blue Hyaluronic Gel Moisturizer ($40), Water Bank Blue Hyaluronic Eye Cream ($43), Water Bank Blue Hyaluronic Exfoliating Toner ($31), and Water Bank Blue Hyaluronic Revitalizing Toner ($31), all available at sephora.com and laneige.com.

And it's paying off. I met with Sweeney at a celebration for her Laneige partnership in NYC less than 24 hours after she attended Vanity Fair's 2022 Oscars After Party in LA – and she looked highly moisturized. (She credits her glow to help from her glam team).

"I'm not lying when I say I washed my face in the airplane sink," Sweeney laughs. "My number one travel skincare tip is to always travel with clean skin. Don't wear any makeup because you're not impressing anybody. I put all of my skincare on when I'm on the plane, then I put the face mask on, and then the actual face mask for COVID. That way when I'm asleep or it's just sitting on my skin for a really long time, I have a barrier of protection."

While raw skin played a big part in season two's overall makeup vibe, there were still bold, colorful eye makeup moments that Euphoria (and makeup fans) have come to expect from the show. When asked her favorite look of Cassie's this season, Sweeney is quick to say the pastel '60s-inspired cat eye with robin's egg blue eyeshadow Cassie wore during her manic week of trying to impress Nate Jacobs at school.

"Probably the bathroom scene when Cassie screams, 'I've never, ever been happier,'" Sweeney says of her favorite makeup look. "It was really pretty; it was very Brigitte Bardot-esque. But I also loved going makeup-free. So, the episode after the crazy party and she was throwing up and she's just not wearing any makeup – I liked that."

VIDEO: Angus Cloud Talks Euphoria Season 2

Speaking of Cassie's now-iconic "I've never, ever been happier" line, Sweeney loves that it's become a TikTok trend.

"That's actually the first scene we filmed coming back. So I had to map out in my brain what would have happened to Cassie in the first two episodes in order to get to that moment," she says. "I had no idea that it was going to become what it has because I filmed it 10 months earlier. So when I saw it and everyone was meme-ing it and tweeting it, I was like, holy shit!"