Many users do not desire to interact with underage users for many reasons. Some underage users may wish to opt out of seeing 18+ users so they may bond with people closer to them in age or perhaps for safety. I think a functionality to

• mark your account as 18+
• hide content from accounts who didn't mark self as 18+
• hide content from accounts who marked self as 18+ would be very useful to those users and set a higher standard of personalized experience for users engaging with social media.