With parenting it’s not a case where you have 100% airtight control over everything with no possible leaks. It’s a spectrum where you impose expectations combined with some controls.

The parents I’ve seen who give up and make no efforts because they think it’s impossible to perfect control everything don’t have great outcomes. This applies to everything from internet to drinking alcohol and more.

I went through it and circumvented it completely in the 90s when the only way online was a computer with a modem in the living room. It's so much easier today, its absolutely trivial to circumvent anything you're doing. Old smartphones from "a friend's brother" are easily hidden and can be used on wifi you don't control.

All it takes is the kid wanting to go behind your back, the rest becomes easy for them. The only chance you have is establishing a good relationship with your kid and instilling good values. You can't actually control them online unless you lock down their life like a supermax prison.