As a parent, what I find effective are content rating systems, be it for movies, games or apps, along with the ability to control and fine-tune them.

For example, with Apple's parental controls, I can blanket-decline access to Social Media apps, or to apps recommended for a specific age or older, and I can also allow exceptions as I see it fit (for example, my kids have no access to WhatsApp but they are allowed to use Signal, both have the same age recommendations)

This moves the responsibility for age verification to me, the parent, and provides me with suitable tools to monitor this. With this, there is no need for my kid or me to upload sensitive data or go through some bad age verification implementation.

Websites are more difficult to control, but not impossible.

Long story short - improve tooling for parents that allow more centralized control instead of mandating social media to do the age verification on their end.