I’m not sure how this currently works. (I’m still on a much older device). If I recall correctly, @werner_noebauer set up something like this a while ago (hopefully he’ll notice the mention and enlighten us).
Most of Fairphone OS is pure Android 6 (at the moment). I wouldn’t know which guide to recommend, but there should be plenty of general Android tutorials out there (though disappointingly, Google appears to have removed most of the help sections relating to Android 6).
Apparently, it’s either under:
or the place mentioned in the post above. As said, I can’t check.