This isn't the first time this has happened in "children's" communities. Is there some way to prove a person is under 18? We can prove that someone is over 18

This isn't the first time this has happened in "children's" communities. Is there some way to prove a person is under 18? We can prove that someone is over 18 via ID's or using credit cards as a proxy, but is there a way to keep adults out and let children in? Roblox seems like a space that could potentially be limited to children. I've never met an adult with an interest (anecdata, perhaps it doesn't generalize).