This is how it worked out in Russia. First, around 10 years ago, they adopted very limited laws that required ISPs to block websites. Things like drugs and suicide, with the classic rationale "won't someone please think of the children". Then piracy websites were added to that. Fast forward to now, ISPs were mandated to install black-box "ТСПУ" devices on their networks, "to protect against threats", so now Roskomnadzor doesn't even pretend to care about the law. Half the internet is broken. More if you're on mobile data. Everyone knows what a VPN is. I personally have set up DPI bypass tools for many of my relatives.
In other words, if you censor enough of the internet that your population knows ways around that, your censorship simply ceases being effective.