The scope of the things we already do to "protect the children" is tremendous. None of them have, will, or could prevent them from continuing to use it as an excuse for things that should never be done.
You seem to have jumped from "protecting children" to accusing them of an unrelated war crime for not censoring things aggressively enough.
On top of that, the relevant law they would have to comply with in those countries would be the laws of those countries, and those are the governments committing the genocides.
The governments won't protect them either. The governments are the ones enabling these corporations to exist and facilitate harm towards children. Maybe they shouldn't be allowed to have those corporations.
They are doing something which is not a solution but can fake being a solution, so that the masses will accept it. An actual solution would be to regulate these social media, to prohibit addictive and manipulative algorithms.
Maybe OS vendors should stop trying to sell ads and instead fix their operating systems so that parents can responsibly monitor their children's online activity in a way that promotes both parental responsibility, and children's human rights ... but of course, that would require OS vendors to stop selling ads.