In late September, at Charli XCX and Troye Sivan’s Madison Square Garden Sweat tour stop, Ella Emhoff, the stepdaughter of Vice President Kamala Harris, showed up in a custom knit green beanie with the word “brat” written in big letters across her forehead. When I asked her where she had gotten the beanie, intent on securing one of my own, she pointed to her friend Bailey Goldberg, who was wearing a matching hat.
“People are just...