Just watch a bunch of advanced math and science videos and you're good :)
YouTube is going to use AI to guess your age to determine if the content you're watching is appropriate for you.
https://www.theguardian.com/technology/2025/jul/30/youtube-google-ai-age-verification
"YouTube’s AI will assess a user’s age via multiple behavioral factors, including what kind of videos the user searches for, the categories of videos they watch, and how long the account has been active."
Discussion
If you think they will stop at this, I want what you are smoking.