In what program?
In MS-Word ALT+H followed by AO moves the indent level out, or by AI moves the indent level in deeper. I'm also not clear if you're asking for a way to change how NVDA announces indentation or actually changing indentation, but I'm going to presume the latter.
Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363
Power is being told you're not loved and not being destroyed by it.