LG 43UN700-B
3840 x 2160 Pixels, 43"
LG 43UN700-B
3840 x 2160 Pixels, 43"
This is not so much a monitor problem as a software problem.
Maybe the LG "On screen control" software also works with this monitor.
With other monitors, it can "partition" the screen so that the windows do not take up the full screen.
There may be other software that does exactly what you want.
I operate this screen on a 27" iMac as well as on a "real" Windows PC 😜. With both systems, I can freely arrange the windows in any way I want. If you want to use fixed divisions, such as halving, quartering, etc., I recommend the "Magnet" utility from the App Store.
I am running this screen under Windows. There is no problem to use multiple windows. I can especially recommend Microsoft Power Tools to easily arrange the windows on such a large screen.
I don't think your problem with arranging the windows has anything to do with the monitor. I assume it is a problem with the macOS. My suggestion: get a real Windows PC. I haven't heard from anyone that they can't