That's just not possible in practice. There's lots of people who enjoy publishing their sex, not commercially. There's no place under a single jurisdiction that can be filtered or required to prove age. Any social network will contain groups of people using it to distribute porn. When common ones are closed, dedicated ones are created.

I don’t understand what you are saying. The government can force providers to make their users prove their age. And people can violate the law and try to avoid this.