Hi,
I'm Rodell, Independent Advisor and a Microsoft User like you. Let me help you out with your concern.
Yes, you can mute all participants in a team meeting right from within the call screen. Teams will show a Mute all option after a team meeting is being conducted.
However, there are two roles in a meeting. Presenter, same kind of privileges as the organizer and Attendees will be restricted to a few options, one of which includes muting participants.
Hope this information helps. Please let me know if you have any further questions.