Kids only have access to the Internet if someone gives them that access. Generally speaking, that's going to be at home, on a phone, at school, or on a friend's device.
Parents already have the tools to regulate what their kids can do online through existing parental control tools baked into mobile OSes and apps. So a solution like this is superfluous.
Schools lock down their devices already, so that's a non-issue.
If they're on a friend's device, that's not something age-verification legislation can address unless they expect the device to take a face scan every 30 seconds to verify that the user using the device is the one who authenticated their age already.
So again I ask - what problem are we solving exactly?