Isabelle Huppert on Her Dior Wardrobe in New Film, Love of Shoes and Those Viral Balenciaga Looks

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For Isabelle Huppert, fashion reigns supreme.

In the new 1950s-set film Mrs. Harris Goes to Paris, the Oscar nominee plays Claudine Colbert, the righthand person to Christian Dior at the House of Dior unwilling to open their doors to the non-elite. Enter the titular Ada Harris (played by Lesley Manville), a charming, working-class British housekeeper who is recently widowed and saved her cash to travel to Paris for her dream Dior dress.

Huppert tells PEOPLE the film was "really a lot of fun to do," primarily because it meant being decked out in elegant Dior outfits at all times, as recreated by Oscar-winning costume designer Jenny Beavan.

"It was nice to be nicely dressed up and made up in the beautiful, old Dior dresses I was wearing," she says, joking too that she wishes she "could have taken with me the makeup girl and the hairdresser" after filming wrapped. (Shout out to her personal stylist for the film, Szandra Bíró.)

The French actress tells PEOPLE that to her, fashion is all about self-expression.

"Clothes either make you more visible or more discreet. It says a lot about how you want to be seen and what you want to say about yourself. In a way, clothes and fashion is so fascinating and fascinates people because it defines a human being," she explains.

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focus features Lesley Manville in Mrs. Harris Goes to Paris (2022)

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First and foremost is the shoe, she says: "The shoes are very important — even more so when you're an actress, because I think you find a role in your shoes. Whether you work with flat shoes or whether you work with high-heeled shoes, it gives you a different body attitude. It says a lot about who you are and who you have to play, in a way."

The star's been rocking Balenciaga looks of late, stepping out on the Cannes Film Festival red carpet in a sleek, all-green dress with heels, for example. "I feel great when I wear all of Balenciaga's dresses and outfits. Especially that green dress was wonderful."

She adds that the "genius" Balenciaga looks are "very easy to wear" and applauds the "smart" designs for blending elements "from the past and from the future."

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Huppert calls her character Claudine Colbert in Mrs. Harris Goes to Paris, which is an adaptation of the 1958 novel, "not a very nice person" who has her eyes opened by Mrs. Harris' push for inclusivity in the fashion world.

"She's not always very sympathetic because she's full of a little power. But of course, she's very funny too because the way she talks to people. Through Mrs. Harris' insight, her own life is going to be changed. She becomes really aware of something because she only talks to very rich, very wealthy people."

The actress says on the inside, Colbert is "quite fragile," and "her inner life, private life is completely different from the appearance of the life she has in the Dior house" — something she says most can relate to.

"In a way, that's very universal. Everybody has always a double — sometimes a triple — layer of who you are. You are a certain person when you relate in a social position and a certain person within yourself, if you are completely alone with your fragility, with your weakness, with your needs, with your unaccomplished wishes," says Huppert. "This is exactly what we find out about Madame Colbert. She has a certain appearance, and deep inside she's completely different."

Mrs. Harris Goes to Paris is in theaters Friday.