I find my login screen very small so I tried to make the content larger by editing
/etc/sddm.conf.d/kde_settings.conf
declaring EnableHiDPI=false respective true.
That didn't change a thing.
Setting ServerArguments affected the DE itself too in a bad way.

Whats the best way to make the login content larger?

[Wayland]
EnableHiDPI=false

[X11]
EnableHiDPI=false
#ServerArguments=-nolisten tcp -dpi 168

I know scaling under settings adjusts your desktop ect had to do it on the mac but I can not remb if it applied to the login screen to.

This should be working and not change stuff on the Plasma Desktop, additionally you should be able to change this via xorg conf