I'll sure try, helo292, here's Apple web page for your MacBook pro, what you want is 2 independent/extended displays... NOT mirrored, independent...so that the external monitor you are using is an extension of the built in one, and you can move your zoom over to the other monitor, is that sorta correct??
anways, see link...
MacBook Pro - Tech Specs - Apple (CA)
referring back to that page, with the M3 mode, you have 2 thunderbolt /USB4 ports with support for Displayport and Thunderbolt 3, with the M3 Pro and m3 max, you get 3 ports, with support for thunderbolt 4, which is backwards compatible with Thunderbolt 3 plus displayPort....
anyways, you'd have to go to System Preferences>>>>Display>>>turn on extended displays, do not go for mirrored displays as that would mean whatever you see on your main (built in) monitor, you'd also see on your 2nd monitor(same darn thing)then mess around with "Arrange Displays"....
I don't know exactly who the maker/manufacturer of your external monitor is or its model number so don't know its capabilities, but you can do that, and you can find that info out yourself, as you're the closest person to that monitor....Unless you've managed to invent a working flying carpet, teleportation, have a magic genie close at hand or are willing to buy me a plane ticket to your place to solve your problem....this is the best answer I have for you now....
John B