I don’t think social media use by kids can be contained any more than drugs, video games, outdoors mischief or any of the other coping methods kids use in a society that forces their parents to work to exhaustion.
Maybe more social programs, shorter work hours so parents can actually engage their kids, and community efforts to engage kids will pull them from their coping methods of choice.
As it is, social media is restricted to 13+ (since most platforms rather do that than child-safe their platforms – there are standards) but kids nationwide (if not worldwide) just lie about their age as they do with porn access. For a while this was a major source of (unenforced) CFAA violations.
Here in the US not even the Democratic party is going to help us change to a society that cares for and protects our kids, and all but criminalizes our teens, so until there is a radical sweep and reform of societal norms, our kids are just screwed.
The first step is recognizing that you may love your kid, but our society collectively hates all minor demographics and treats them as a market to exploit, or a pest. This has been the case prior to the boomers and makes for an intergenerational mental health crisis.