While everyone is separated into their respective breakout rooms, the host and participants can use the chat feature to message everyone in the meeting, members of the breakout room, or the host of the meeting.
Sending an in-meeting public chat
Only the host can broadcast messages that all the participants will receive.
Click Chat in the bottom menu bar.
Select With everyone.
Input your message in the chatbox and send.
Sending an in-meeting breakout room chat
You can only message people who are in the same breakout room as you.
Click Chat in the bottom menu bar.
Select This room.
Input your message in the chatbox and send.
Sending an in-meeting breakout room private chat to the host