Volume control for backup alarm

I’d like to be able to control the volume for the “backup alarm” that comes on if you don’t interact with the normal alarm. The max volume on my phone is too insanely loud - loud enough to wake up the whole building and damage my hearing. I like the ‘backup alarm’ feature but I never want anything to play that loud, under any circumstance. So right now, without volume control, I have no choice but to set it to silent.