Roblox communication is not one single chat switch. A child may have access to messages inside a game but not direct chat, or to Party chat with a limited group but not every connection.
Age checks, parental controls, the child's age group and local rules all affect what appears.
Game or experience chat
This is the chat shown while playing. Messages may be visible to the server or a smaller team, depending on how the creator built the game.
Roblox filters messages, and creators can disable chat or add preset communication. The presence of a filter does not mean every unkind or manipulative message will be prevented.
Children should know that a public server is not a private conversation, even when only one player appears to be replying.
Direct chat
Direct chat lets eligible users communicate outside a running game. It can keep a conversation going for longer and make contact feel more private.
Review who may contact the child and which connections already exist. Under-16 users may need parental consent, and age checks can still be required.
Party chat
Party keeps a small group together across games and can include chat for eligible users. Roblox currently supports parties of up to six people.
A Party invitation should not be treated as harmless simply because it is a built-in feature. Children should accept only people they know and remove anybody pressuring them to move to another app.