Youtube does have least some level of sensitive content age walling, though it's not applied to that many things. it's a prompt that says it contains suggestive content or whatever and asks if you're okay viewing it, and also requires you to be logged into an account to see it
edit: ok slightly misremembered what it says. but it is, without a doubt, an age gate
https://gamefaqs.gamespot.com/a/forum/d/dc056089.png
THIS IS WHAT I HATE A BOUT EVREY WEBSITE!! THERES SO MUCH PEOPLE READING AND POSTING STUIPED STUFF