As michev said, attendees already in the meeting can work properly. The overflow cannot join the meeting.
For large meeting, live event is a good choice. It could cover 10000 participants. Please note that a live event can be only started once. For more information, please refer to this article.
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.