OK, I've spent so much time on this application, here are some tips for bigger meetings and how to handle them on Zoom.
On a Mac, turn on dual monitor in the Zoom/Preferences, this doesn't do what you think and is more general. What it does is give you two windows, so you can actually manage. Without this, the main display window and the participants are in a single window. That wouldn't matter much except you now get way more flexibility in layout.
I like to put the presentation windows in the top quarter and then change the member view Gallery and then make that so I can see the people below get the maximum view of 7x7 or 49 people and you can track if people are getting it. This screen has to be about 60% of the distance so you can see it. Frustratingly half the screen is not enough, you need just a bit more. If you have 7x6 or 42 users, then exactly half the screen is enough space.
Then you click open the chat window and place it over on the side underneath the main window. The nice thing about this is the chat window is in the lower left and you can really read it. Too often the chat is too small in large conferences and it is nice to have that window always available.
Also remember that in the chat window, the last person sent is sticky, so don't be that person who sends a wide crack meant for one person, the Everyone in the group.
Note that Zoom is pretty smart about how it orders the people. If there is video, those folks will be first in the list, so most of the time you just need to look at the first pane and see the first 49 folks.
Now to go Zoom > Settings > Video > Hide non-video participants There used to be a way to not show thumbnails of people who are non-video and now you are not waste real estated
If you do not want to do this, then the only way to get 7x7 and the picture is to go to fullscreen and then drag the bar between the presentation and the people to about halfway.