You teach them about moderation, you give them the tools to make their own choices, and you protect them from the obvious/bad outcomes that would cause irreparable harm.

So like, add a network filter for gore/porn up to a certain age, and try to do a good job of showing how to invest their time as a reward function rather than the instant gratification path.

But ultimately, babying them will prevent them from growing, and the moment they get out of your clutches (how they'll see it) they'll binge/overindulge and not have anyone to stop the irreversible mistakes from happening.

Limiting technology access creates a perverse relationship between the kid and tech. If you want your kid to see technology as a tool, not as a reward, you can't treat it like a reward. It's super easy, but it sets the wrong example.