nix-config/systems/common/core/xorg_plasma.nix

{ 
     services.xserver = {
         # Enable the X11 windowing system
         enable = true;
     
         # Enable Keymap
         xkb = {
             layout = "us";
             # variant = "qwerty";
             # model = "thinkpad";
         };
         # KDE X
     displayManager.sddm.enable = true;
     }; 
}