We set it as the used DM on plasma/kde all installs now, but only applies to new installs.
On older installs you can simply switch them too:
sudo pacman -Syu plasma-login-manager
sudo systemctl -f enable plasmalogin
after reboot it will be used.
In case you can cleanup after you:
sudo pacman -R sddm sddm-kcm eos-sddm-theme
(removing sddm configs and deps)
But you can also keep it in case..