If you like to go the other way, via DM as you apparently have been used to, look here:
https://wiki.archlinux.org/title/SDDM#Installation
That way you can choose to boot into Plasma or Lxqt from the DM’s greeter (“login-page” as you named it).
In that case it makes sense to either delete the previously edited ~/.xinitrc (in your home-folder), or just overwrite it with the xorg-xinit standard-file, via:
sudo cp /etc/X11/xinit/xinitrc ~/.xinitrc