Assign external monitor as one of virtual spaces?

Is it possible to assign external monitor as attached to one of the spaces?
Have external monitor connected to some projector/big screen sharing something to ppl in a way when you change visible virtual space on primary monitor - external monitor is not disturbed.

Additional question:
Is it possible to replicate external monitor to one of the spaces on primary monitor.
(or make external monitor to replicate always one of the spaces, not always visible one)

When you share something to projector you can either look at other spaces on primary monitor (invisible for auditory) or see same as on external monitor (as simple as change visible space)
yes, I know that I can attach external monitor as “replicate primary” but then I’ll expose everything, what is not intended.