After system startup, the X Window System GUI login interface is not displaying.

To make the system boot into GUI mode by default, use:

bash

systemctl set-default graphical.target

This sets the default target (similar to runlevel 5) to start the GUI.

isolate immediately switches to the GUI target but doesn’t persist.

unmask and enable are only useful if the service is known and named xwindow.service, which is usually not the case (it's typically gdm, lightdm, or graphical.target).