As Roblox notes in its announcement, the age check verification uses Facial Age Estimation or ID verification. Roblox says ...

Roblox will now require age checks for communications between users, with facial age estimation (FAE) as a biometric option.

Roblox has launched facial age checks as a requirement for all users who want to access communication features and implemented age-based chats.

Roblox must also account for bad actors who try to use fake photos or pictures of another person to evade accurate age ...