Every Sunday afternoon, shoppers descend on Bella McFadden’s Depop page for the chance to be dressed like ’90s cult film characters, “sk8r girls” and “Y2K mall goths .” Ms. McFadden, who is 23 and lives in Los Angeles, is something of a “Depop mogul”: Sales of her thrift-store finds have taken off on the popular e-commerce app, where she has more than 500,000 followers who admire her early-aughts aesthetics. They long to be styled by her. They know her as Internet Girl.

For $150 plus shipping, Ms. McFadden’s fans can name a visual theme or inspiration, send over their body measurements and astrological sign, and receive two to three outfits customized to their specifications, with matching accessories. The looks — pulled from a mix of thrifted items, dead stock and Ms. McFadden’s own designs — range from bubbly (a baby tee that reads “All this and brains too” paired with a Hello Kitty purse) to gothic (a black vinyl mini dress and a bat-adorned pendant). And the chance to be outfitted by Internet Girl is competitive. O nly 20 lucky buyers can get the customized clothing kits (called “Styled by iGirl” bundles) each week .

Ms. McFadden, who has been selling on Depop for three years now, introduced this business model in early 2018, when she was still operating out of the house she was renting in Canada. “Because I was living in Winnipeg at the time, I wasn’t really getting any opportunity to do styling work,” she said. “I found when I was styling the products at home that I was pulling together all these iconic outfits. I was just like, ‘Damn, I should be selling this.’”