Looking for way to split monitor into 2 screen like xrandr did

Hi.

I’m looking for way to split 4k monitor into 2 screen.
But not by tiling.

If you ask why, I’m tired to waiting 3840x1600 38 inch monitor for years, so I just buy 40~43 inch oled and split it.
And actually, split is secondary option if I can just use as 3840x1600, adjust screen to top of the TV and let bottom blank.

I tried some search but on wayland - plasma, it just not work cause kwin is not support it.

Is there any add on or something that I missed?
Should I just use xorg? or there will be update some day in future?