Auto lock

If it's in Low Power Mode, Auto-Lock is 30 seconds. You can either wait until the phone is charged or you can turn off the Low Power Mode option. See: Use Low Power Mode to save battery life on your iPhone - Apple Support

Well.

Mine currently denies me the ability to change the time. Saying that if it’s in low battery mode it times out at 30 seconds? It’s plugged in and charging at 32%. Do I need to wait until it’s fully charged?

Flabbergasted.

Go to Settings > Display & Brightness > Auto-Lock and change the time there.

I figured it out!

I had to turn off low battery mode first.

Then I could change the time.

Satisfied.