I found blocking things is full on, time consuming and never really works effectively enough. There’s always a way to see things that you want to see and if its forbidden, the curiosity is stronger.
Preference is approaching conversation with the kid(s). Take some time to watch things with them. The kid needs to learn critical thinking using logic and reasoning. Teaching these skills, and to not take everything at face value is probably where I would direct my energies. Wish I had better advice, but harbouring good debate without getting too emotional/personal is a skill worth learning.