I am just getting started with Manjaro, long time Fedora user. I would like to run KDE Plasma and XCFE however they each have their own recommended Display Manager lightDM vs SDDM.
Is there a way to use lightDM when I login to the XCFE desktop and use SDDM when I log into KDE?
No, that’s not possible. I do believe that lightdm supports logging into Plasma — or at least, it used to — but I’m not sure whether sddm supports logging into Xfce.
What I can tell you however is that Plasma 6 prefers Wayland — it also still supports X11 — but to the best of my knowledge, lightdm is X11-only.