This locked post didn’t go far enough. Where in /etc/sddm.conf.d/?Section? or wherever else for global application does such a script belong? Reading man sddm.conf I only see three, all of whose directions would seem to usurp defaults rather than supplement.
Primarily I wish to continue with X11 as long as possible and continue with xrandr commands that preferably apply initially to the greeter itself, but at least flow through into whatever user session gets started. Currently, using TDM or KDM3, I put the xrandr command(s) in /etc/X11/xinit/xinitrc.d/, and they apparently get applied (or sustained?) only for sessions other than Plasma (at least in KDE3 and TDE; perhaps none other?).
Secondarily, or maybe in conjunction, now that defaults are being (Leap) or have been (TW/SR) moved to /usr/etc/ from /etc/, is /etc/X11/Xresources still the optimal place for global Xft.dpi: override?
One overall object of all this has to do the software industry’s fixation on making everything tiny, requiring tiny UI be used with difficulty in order to determine how to and then make things big enough, rather than starting out big, and letting users who like tiny use a larger a UI that virtually anybody and everybody can use without pain for switching to smaller.
DisplayServer=
Select the display server to use for the greeter. Valid values are:
• x11: X server running as root.
• x11-user: X server running as unprivileged user.
• wayland: Wayland compositor as unprivileged user. (Experimental)
Default value is "x11". For x11-user you might need to configure Xorg.wrap(1).
DisplayCommand=
Path of script to execute when starting the display server. The script will be executed as root when General.DisplayServer is “x11”,
otherwise as sddm user. Default value is “/usr/share/sddm/scripts/Xsetup”.
I read that several times. That language reads like said script will usurp all of whatever /usr/share/sddm/scripts/Xsetup contains, not supplement it, so I kept on looking.
Where I would like is the same place they already are, multiple files in a specific OEM .d/ directory that varies by distro, and whose contained files I swap around according to which displays, how many displays, and which port(s) to which they are connected for that activity, which here is in an oft repeated state of change. The filenames vary according to what they contain/do.
Anyway I gave it a few proof of concept stabs:
Try 1 in Plasma:
Same failure as before. Try 2 almost didn’t happen. I intended to disable KScreen and try again, but that option seems to be absent from System Settings in v6. So, I tried adding the . before the filename, and got good result. Then I tried once more without the ., but before logging back in I remembered to Ctrl-Alt-BS-BS first. I think I forgot that the first try without .. I looked in man bash to see what that . means but didn’t spot anything relevant. In tdmrc and kdmrc there is an option I always use to restart DM on session logout, which I don’t see in man sddm.conf. Anyway, Plasma try 3:
It’s progress, but surely there must be something I’m forgetting about… MinimumVT=7 is being ignored, NLA, needs workaround. And, I’d love to find a way to do in similar manner what was rejected in upstream bug 509, inject Xft.dpi value calculated from the server value seen running xdpyinfo.
Gracias. Once upon a time I knew it was in “Background Services”, where most bling-bloat can be disabled, and that it goes in ~/.config/kded5rc:
[Module-kscreen]
autoload=false
Now it’s in my KDE notes where I ought to be able to find it when next I forget, while that user instance has only 4 checkboxes checked in background services, and string “true” only 4 places in kded5rc. Unfortunately, it doesn’t help to have it off…
That was what I started with. When first try failed, I changed to xrdb -merge -nocpp <<< 'Xft.dpi: 120', which I thought for a while worked. Somewhere along the way I went into System Settings > Fonts to turn on Force font DPI to 120, and then forgot to change it back until checking after your #11 reply. So, I’m apparently back to square one. Neither of the two methods are sticking in Plasma using the current scripting, while IceWM is fine:
The whole point is certain global defaults that come with every OS are unacceptable to me, so I wish to make use of /etc/ to change them - 1 time for each OS installation - and avoid having to find all the places that must be changed all over again for each DE and for each and every user created. If any particular user wants to further adjust, then that user can use his own DE settings.
The little I’ve dabbled with “scaling” has been entirely frustration. X DPI manipulation was doing just fine here until GTK foisted forced Xft.dpi in v3.17 on every X environment that needed to use any GTK3 app.
Most modern DEs typically have their own font DPI settings, and they often override what’s set via the X server anyway. Your ‘solution’ needs to be invoked in the DE concerned.
This isn’t just about fonts. I thought I had this covered in post #14.
Modern isn’t anything like equivalent to better. The Gnome Way I ruled out more than two decades ago. Plasma6 has not shown me much promise so far, even less so in Wayland and/or with multiple displays. Thank goodness that good old gold old trusty 3.5 and TDE have not been blocked from continuing with little more assistance than xrandr can provide. Still, I need to know what I need to know, something KDE has made difficult with every major upgrade, and copious releases in-between, since introducing v4. It hasn’t stopped me from trying yet, but tangled path indeed.
And, I’d love to find a way to do in similar manner what was rejected in 
Unfortunately, it doesn’t help to have it off…