@derek what I did on my son's machine was installing AdGuard. It can be configured pretty extensively.

@derek Composing a comprehensive allowlist, we stopped using the word whitelist a while ago, depends on a lot of things. First of all, where are you located? Britain, Canada, France?

A good starting point can be the TV-channels you children watch. Check out all the websites related to programmes on those channels and go from there.

Another route is to just switch your entire household over to a save DNS. The European Commission has started secure DNS servers, see:
https://www.joindns4.eu/for-public