if you didn't state your age explicitly and i'm following you: you probably left an indication of your age group in recent activity on your neocities profile, in recent journals you've posted in your site, or in the bio of any social media you've linked from your neocities site. obviously i don't go out of my way to search, that'd be weird. but i always make sure i only interact if i can confirm you're at least 21.
i love friendship and online connections, and i want to seek those healthily with grown adults.