Hello
hope this is the right place for the question
i have a 14" laptop 2880x1800 res and a usb monitor also 14" with 1920x1080 and both monitors are scaled together with the user interface scale setting in display options, can i un-couple it? things look perfect on the lappy monitor but HUGH and almost nothing fits on the external.
does it have to be on or off on both at the same time? question is in regards to xorg, seems weyland has it down pat.
I don’t think Xorg an do this.
Then why not use Wayland?
X11 is a 1980s display protocol. Its developers probably never imagined that people would need different scaling factors on multiple displays.
Plasma Wayland works great on AMD graphics. You should use it.
oh i’ll use wayland then. but i still would like to know of its doable what i want with xorg
You really would be better off just sticking to Wayland. There is very little focus on Plasma X11 by KDE developers nowadays, as these 2 comments by a KDE developer in this thread on the KDE Discuss forum indicate:
KDE have made it quite clear over the past year or two that Plasma’s future is Wayland. They’ve even recently split the kwin repos so that new features can be rolled out to Plasma Wayland without having to add them to Plasma X11:
Future of KWin/X11
KWin/X11 will be still maintained for the foreseeable future. But that maintenance work will boil down to fixing build errors, adapting to new KDE Frameworks and Plasma APIs, and backporting window-related fixes from KWin/Wayland. There are no plans to drop KWin/X11 in the Plasma 6 lifecycle, although it’s highly possible that it will happen in Plasma 7.
KWin/X11 won’t receive new features anymore; until recently, it received new features that had been developed against KWin/Wayland passively (because both lived in the same repository). However, it might be actually a good thing because the X11 session doesn’t receive that much testing nowadays.
You could set the same resolution on both (I do it), but in this case I don’t think the aspect ratios match. Also that’s not really what you’re asking for.
You can apply a scale or transform using xrandr. This is 
from an old script I still have lying around, I think I used it for a while, but it was some time ago and my memory is vague.
xrandr --output HDMI-A-1 --mode 1920x1080 --pos 3840x0 --scale 2x2
xrandr --output HDMI-A-0 --mode 3840x2160 --pos 0x0 --scale 1x1
Don’t try changing DPI etc, it’s a rabbit hole and never works well.
Wayland is genuinely more versatile when it comes to multiple monitors. Plus, it’s more performant generally; Nvidia graphics users still suffer the occasional hiccup.
Important to note is that xrandr doesn’t work with Wayland, but there are several alternatives - wlr-randr comes to mind.
Generally speaking there is little need to manually set resolutions as they are usually provided through EDID (Extended Display Identification Data).
“Displays greater than 800x600? Impossible!”
– 1980 Technician
wlr-randr won’t work, as Manjaro doesn’t support wlr-output-management-unstable-v1. I just installed & tried to run it:
wlr-randr
compositor doesn't support wlr-output-management-unstable-v1
I remember this being discussed last month, albeit for a GNOME installation:
There is also a wl-randr, apparently, but a cursory search didn’t find much reference to it.
I’ve personally not needed to rely on xrandr (or the like) for many years; an old Tseng Labs Nvidia clone, if I recall.