documentation/docs/admin-guide/configuration/desktop/multiscreen_setup.md

Multi Screen Configuration

Multi screen configurations on systems with Nvidia cards need to be done with the Nvidia Driver Tool. Arrange all the screens as needed, afterwards export the configuration via the tool.

The saved configuration then needs to be deployed to /etc/X11/xorg.conf.d/11-screen.conf via hiera as follows (this ensures that the configuration will be persistent over time):

files::files:
   /etc/X11/xorg.conf.d/11-screen.conf:
      mode: "0644"
      owner: "root"
      content: |
         # nvidia-settings: X configuration file generated by nvidia-settings
         # nvidia-settings:  version 470.256.02

         Section "ServerLayout"
            Identifier     "Layout0"
            Screen      0  "Screen0" 0 0
            InputDevice    "Keyboard0" "CoreKeyboard"
            InputDevice    "Mouse0" "CorePointer"
            Option         "Xinerama" "0"
         EndSection

# ... and so on ...