How do you prevent minors from going on your YouTube channel?

Hello, I have a YouTube channel that deals with sensitive topics and I do not feel it's appropriate for minors. (To be honest the Internet as a whole isn't safe for minors)

There's no explicit content, so I'm not sure if putting the 18+ restriction makes sense or not.

Maybe there isn't a way to actually do this. But I at least want to hear other people's suggestions.