If that's what I'm thinking of, then it works well for access at a home via wifi, but it doesn't address mobile usage over the cellular network.
Balance is important, so while I'm also on the side of generally not restricting the internet, it is worth highlighting that this isn't meant to be foolproof/exhaustive/a silver bullet. It's one small measure aimed at trying to reduce early, accidental, exposure - to material which is far more extreme than what you'd find in a magazine in the shed back in the day. The problem of distorted norms and introducing violence to sexual relationships is affecting children and young adults' mental health, and this is one facet, alongside calls for more appropriate education etc. to try and address that.