Pin Key Attendees on the Screen for Everyone

Pn1995 

I run quite a few large meetings.    

Pinning is a personal user choice for a user's particular screen, it doesn't affect anyone else's view.

Assigning your presenters in advance, will provide you much more meeting control during your meeting.

https://support.microsoft.com/en-us/office/manage-attendee-audio-and-video-permissions-in-teams-meetings-f9db15e1-f46f-46da-95c6-34f9f39e671a

During a meeting you can actively spotlight presenters to make their camera feed appear larger than others in the meeting.   

https://support.microsoft.com/en-us/office/roles-in-a-teams-meeting-c16fa7d0-1666-4dde-8686-0a0bfe16e019?preview=true

If you are screen sharing during a meeting, the screen will always be larger and move and shrink the spotlighted cameras off to the side.    If you are more interested in a specifically a talking head discussion, then stop screen sharing momentarily and resume screen sharing after the talking head discussion is finished.