Parental control software is counterproductive, and will generally only lead to them trying to outsmart you, which is a bad precedent. If you really want to keep your kids safe online, the most important thing to do is establish trust and understanding with them that the boundaries you set are important and reasonable. You need to respect them as people, and they need to understand and appreciate why you set the limits that you do.

On top of that, you need to supervise them, and even then, they should not be allowed to use social media, which ought to be 18+ anyways.

I understand this is all a lot to ask in our society. There is no "good" answer to this problem. But we should all try to do the best we can, and not forget that big tech puts hundreds of millions, if not billions, into making social media as addictive as possible. I'd say we're at a point where it's sensible to conclude it's now more addictive and harmful than tobacco, though our society has yet to come to terms with this fact. Even if we put a stop to it now (we won't), our current social media infrastructure will likely haunt us for centuries.