If using sddm, you can add:
cat /etc/sddm.conf.d/00-general.conf
[XDisplay]
MinimumVT=7
# boo#1089932
EnableHiDPI=true
[General]
HaltCommand=
Numlock=on
RebootCommand=
[Users]
# boo#979775
ReuseSession=true
MaximumUid=65000
MinimumUid=1000
If using sddm, you can add:
cat /etc/sddm.conf.d/00-general.conf
[XDisplay]
MinimumVT=7
# boo#1089932
EnableHiDPI=true
[General]
HaltCommand=
Numlock=on
RebootCommand=
[Users]
# boo#979775
ReuseSession=true
MaximumUid=65000
MinimumUid=1000