I stare at my iphone and start to wonder where I get to change my dns settings...? So I've just spent five minutes poking around and I haven't found it yet. So I've just googled it, and apparently you need 3rd-party apps to do it...
Now, interestingly, I could imagine kids doing it rote if someone just tells them how to install the an access-4chan app etc. For example, a couple of years ago I watched in horror as a 10yo friend of my kids demonstrated how to download an app (not from the app store) that would create a vpn to stop the app-store from being able to connect and discovering and uninstalling all the pirated games this kid then proceeded to install for my grateful kids! And her hands flew over the screen, tapping away and typing in English, which is a language she didn't speak let alone write in! Amazing rote. And very scary to tidy up after her!
So yeah, kids will probably circumvent this kind of thing even if parents can't.