Virtual Display - HighDPI scaling?

[dr1pvfx]

I want to create a virtual display that has a native or max res of 3840x2160 pixel

Then i want to "scale it" to 150% so its the equivalent as selecting 2560x1440 pixel on a real mac with a UHD screen connected.

I cant get that behaviour to work, i tried a lot of combinations with hiDPI turned on and off and max and min resolutions e.t.c but it just either gives me the native 2560x1440 or 5K (so 2x of that) but never UHD native scaled to look like 2560x1440 which is what I want

this is for parsec , so i dont want to run higher than native pixels but i want my ui to be larger - pretty much , what am I missing?