Camera recording is not required to start a session on the participant's side. Only screen recording and audio recording is required to start a session on the participant's side.
If you do not wish to record the participant's face, please request participants to 'Not enable camera' when grating permissions before starting a session.
It is not possible for a participant to turn off camera in the middle of a session . So they must choose not to record camera before the actual session begins if they do not wish to have the camera enabled.
However the Moderator can choose to 'Not enable camera' before they join the session or they can choose to turn off camera once the session has begun.