Trust TikTok to coin a new hair trend. Heading into autumn, the #preppyaesthetic is trending with crisp-collared button-downs, blazers, and loafers. And preppy-girl hair is the perfect companion.

We all know what "preppy" means — don't we? If you're older than those in Generation Alpha (anyone born after 2012) you might think of a wealthy person with a particular fashion sense (collared shirts ...