At the risk of being wildly misunderstood:

My kids got help to find kid-friendly things but were essentially free to do pretty much as they pleased online. They were given two tongue-in-cheek guidelines: No porn and no learning how to make bombs.

I think the key is to assume they are good kids who need some help finding what interests them, not bad kids who need a parent jail keeper preventing them from doing bad things.

Having said that, I was fortunate to be stationed in Germany when they were really little with access to only one American TV channel. I had lots of videos for them, not to control content but to give them entertainment. Still, content control was largely baked into the situation.

So I am somewhat self conscious that what worked back in the day may not work now and other disclaimers.

Edit: I will also add that when they were little, we had one computer in a public space. Individual computers in private spaces came much later.