While scheduling a Zoom Meeting, select Off for participants (in the Video section) to ensure that their video will be disabled when joining your meeting.
During a Zoom Meeting, the host or co-host(s) can stop or ask to start a video for specific participants through the Manage Participants feature.
Note - This is done manually per participant. Zoom Meeting does not have the option to start or stop the video for all participants at once during a meeting.
Select Manage Participants
Next to the participant, select More next to their name in the list.
Then select Stop Video.