There is no "indent" key. There are Indent buttons on the Home Tab.
In the paragraph group there are increase indent and decrease indent buttons.
The Tab and Backspace keys can be used to increase and decrease indents if the proper option is set.
File > Options > Proofing > AutoCorrect Options > AutoFormat as you type
00 deleteme 1.png
I have this unchecked. I prefer to do my formatting using Styles rather than direct formatting.