Watch fully charged notifications BEEP

How do I get my iPhone to notify me with a beep (audible sound) that my Apple Watch S6 has fully charged?

I have always received a banner notification on the Lock & Home Screens, (which I don’t work unless I’m actually looking at my iPhone when it comes through), but never an audible notification on either device which I wanted with both newer and older watches & phones.

I DON’T use the Sleep app because it changes my watch face and locks it —two things that mess up the use of my watch at night, so I only have alarms set on the watch itself, using haptics, Do Not Disturb, and Theatre Mode. I’m a light sleeper and don’t want noise for any waking alarms.

iPhone 12 Pro Max

Apple Watch S6

both run latest OS updates.