Keep spatial resolution at expense of fps

Hello.

I use Zoom to see lectures written on blackboard, often ∼3.5 m wide. Sometimes people at the auditorium are lazy to crop/zoom and pan the camera to specific areas. Given my poor internet, Zoom’s incoming video often degrades to the 320×180 resolution—that is, about 1 pixel per centimetre—which is completely unacceptable.

Can I force Zoom to keep receiving 640×360 even when it would result in less than 1 fps temporal resolution? Does it have respective hidden settings?

This is Zoom 5.13.5.431 (Ubuntu, amd64).