Logitech Slim Combo 12.9 Frequently Asked Questions Manual page 5

 +Adjust the backlighting on the Logitech Slim Combo
You can adjust the backlighting of your keyboard from 0% to 100%.

To increase the backlighting, press the Backlighting Level Up key:

To decrease the backlighting, press the Backlighting Level Down key:
 +Language switch key on Logitech Slim Combo keyboards
The language switch shortcut key is on the bottom left of your keyboard.
 +Viewing positions for the Logitech Slim Combo
There are four different viewing positions you can use with your Slim Combo 12.9 and 10.5-inch
cases:

Typing mode

Viewing mode

Facetime mode

Book mode
Typing mode