“Mate, if I’m just showing you what I’m wearing, that’s not gonna get me anywhere. This is Instagram. You can’t deep it,” Mr. Austin said, meaning “take it seriously.” So he pivoted and started posting stuff like “me looking in the mirror, and in the mirror is this really buff guy,” he said. “It was the right turn to make.”

Around the same time, inspired by the multi-hyphenate talent Tyler, the Creator, he introduced a clothing label called Crowd; he now sells to customers as far as Dubai. He used to work at a Subway, but quit when a Crowd pop-up netted him more money in one weekend than he’d previously made in a month. He even wrote an elaborate resignation letter: “Thanks to everyone even Carlos bye Marisa I hope I can transfer my sandwich making skills to my future day to day life.”

As much as anything, “Mary Berry” was a promo for Crowd. (The video is full of Crowd clothes, and a post-video drop was his best-selling to date.) But it was also born of a generational D.I.Y. ethos: Why not do it?

Mr. Austin points to Alex From Glasto, a fellow pasty British teen who won viral fame last summer when he was pulled onstage at Glastonbury by the rapper Dave to perform the hit “Thiago Silva.” Since then, Alex From Glasto has released his own single. “I was like, ‘No offense to him, but if this guy can blow up …” Mr. Austin said, trailing off.

The making and release of “Mary Berry” was tied — breathlessly, naturally — with Instagram documentation: edited fake DMs from Drake asking to get on the remix, surreal footage of Mr. Austin surrounded by a platoon of life-size Mary Berry cardboard cutouts. “I did a video of me throwing a basketball out a window and then the Lakers being like ‘yo, we need to sign you right now,’” he said. The first Instagram Story tracking the journey is just captioned “about to become a full time rapper.”