In Settings, you can adjust what is shown on the external display and what happens when you flip the phone open or closed. You can also make some quick changes directly from the external display.
Go to Settings > External display > Lock screen clockfaces.
Or, unlock the external display, touch & hold its home screen, then touch Lock screen clockface.

Go to Settings > External display > Home screen wallpapers.
Or, unlock the external display, touch & hold its home screen, then touch Wallpapers & shortcuts.
Set the wallpaper:

When your phone is unlocked, swipe the external display to move between panels of information. You can also tap shortcuts to jump directly to a panel.
Go to Settings > External display > Panels, then:


To quickly rearrange panels, unlock the external display, touch & hold its home screen, then tap Manage panels.


Adjust shortcuts:


When you flip the phone closed, your screen automatically locks, and when you unlock the external display, you are back on its home screen. If you want to keep the external display unlocked and continue using the app on it, then set the app to transition.

Select how you want the app to transition between screens when you flip the phone closed:


Flip your phone open to answer an incoming call, and close it to end a call.
To change how your phone handles calls:
Adjust settings:
