If you are the meeting host in Google Meet, you now have the option to mute all participants at once.
The meeting host is the only user in a meeting who can use the “mute all” feature. Once all participants are muted, the meeting host cannot unmute them. However, users will be able to unmute themselves as needed.
Note that at present, this feature is only available when using Meet from a browser on your computer. If the host is using the mobile Meet app, this feature will be added in the coming months.