Not only is enforcement on a judiciary level extremely difficult (the kids as well as the companies have ways and reason to skirt jurisdiction on the borderless Internet) but you have the problem that addictive products will remain addictive even if there are better options out there.
Personal opinion but I think the best way to counter the social media plague for young people will be something akin to making them "uncool in the schoolyards"
My wish would be no laws could be passed unless we have 3/4th of votes and every 10 year old law gets expired unless passed again.
- It wasn't enough to stop sale to minors (they still got them).
- It wasn't enough to run information campaigns in schools and legislate packaging warnings (stuff like this gets blatantly ignored)
What really worked in the US (but even that with a lag of 5-7 Years) was:
1. blanket banning smoking on the media in the 90s
2. progressively blanket banning smoking in the public since the 90s
Edit: formating