I'm not sure if it is exactly the Command that You mean but I use the following One to get my Screen Settings to GDM:
sudo cp ~/.config/monitors.xml /var/lib/gdm3/.config/
I'm not sure if it is exactly the Command that You mean but I use the following One to get my Screen Settings to GDM:
sudo cp ~/.config/monitors.xml /var/lib/gdm3/.config/