I followed a different approach with my son. We gave him a phone pretty early, and didn't even have a lot of rules around it (no family controls, etc).

The agreement I had with him: "Scroll all day, play video games, etc. That is my side of the agreement. And you also do your school work, learn, practice for exams, homework, etc. That is your side of the agreement. I'll trust you. If your grades get worse, i.e. you need help managing device time, we'll review/change this agreement."

We also sat down many times looking at content together, in attempt to teach him what's trust-worthy and what isn't, what's "healthy" and what isn't, etc. And of course we do other things together as well.

So far (knock on wood) my son has managed well - he is 16 now. He organizes his own time, and has learned when to play and when to work. And crucially he has learned when to disconnect from his devices to do what's necessary.

No kid is the same. I am not saying my approach is best or even right, I just offer it as another data point.

We did something similar with our now 12yo. She self-regulates and tries to stay off the worst doom scrolling garbage sites, and tries to explore different sites and such like Pinterest cards and so on. She knows intellectually that the apps and services are designed to suck away attention. This kinda broke my heart but the other day she made a "bored jar" probably based on a Pinterest card which is a jar filled with little scraps of paper with ideas for what to do when you're bored. It felt like I was watching a drowning person trying their best to stay afloat if that makes sense.