Is a father monitoring his son to prevent him from watching what angers Allah on the Internet, despite the son's disapproval and anger, permissible or forbidden, and how can he be prevented without making him angry?

The right of a parent over his child is great and is not forfeited by his disobedience, even if he were a polytheist. The parent who watches forbidden content on the internet must be advised gently. If he does not respond, he can be prevented in a gentle manner, or accompanied during that time. If prevention leads to the parent's anger, then some relatives should be sought to advise him, while using modern technologies to prevent access to pornographic websites.