The teeth have to apply to the social media companies. Fines for under-16 users.
Such a thing would require mandatory age verification of every user of the platform, which is obviously a significant privacy complication.
Maybe, maybe not. Either way, it would be entirely between the social media companies and their users. No blanket requirements across devices or the internet.
I’d add a provision that creates even steeper fines and private liability for retaining any ID, etc. collected to verify age.