Going through the hoops and figuring out how to do the things your parents don't want you to do is a healthy part of growing up, any parent that doesn't take that into account and actually thinks they're going to stop their kid from becoming an adult is making a mistake.

The goals are to remove easy access to damaging material, and to make them do difficult, clever things to get around it, and to make them think you don't know so that they don't outwardly demonstrate exposure. This limits exposure to the worst of what is out there, teaches them agency and problem solving skills, and prevents them from heavily internalizing whatever they are exposed to.

Yes, when they reach a certain age when they start to want to do things on their own, they'll find ways to be exposed to what they want to be exposed to. There's nothing wrong with this.