I'm watching a documentary series at the moment called Social Studies, where they followed a bunch of teenagers who gave them complete access to their social media and screen recorded them for the show. They spoke to one girl, now 18, who talked about how she first got into posting sexy photos of herself well before she was 18. She tells the story about how she followed a baking account and one day she noticed that they posted a sexy picture, and it got way more engagement than any of the baking pictures. Another girl talked about how she used to post photography, but quickly realised that she'd get far more interaction if she posted pictures of herself, and more if she included her body.
Modern society, and social media in particular, is basically grooming teenage girls to objectify and sexualise themselves. Don't get me wrong, teenage girls have always tried to push the boundaries in terms of looking more grown up and trying to show off their looks, but social media has supercharged it, and at the same time put them in contact with a whole world of perverts.