Rotate the screen after app starts

[ocgltd]

I have an Android app which requires the app display in landscape mode - and that works (using the manifest)

We just discovered one user with a SQUARE screen (Unihertz Titan phone). So he doesn't want to be forced to hold his phone sideways since it achieves nothing.

I can figure out how to detect the square screen, but what's the best way to NOT rotate the screen, OR, rotate the screen back to portrait?