My iPhone Xr will ring load on first ring then go to minimum ring after. Why?

Don't worry because this has to do with Face id.

If you go Into the Face id settings turn of facilities attention section.

Then your iphone will stop to stop your sound issue.

I needed days to figure this out.

If you like your iPhone sound the hardest, you can choose late at night in the equalizer.

The option facilities attention section is for people in a meeting, or in curtain situations.

success

Are you picking the phone up before the volume goes down? If so, it is by design.

There is an option where that can be changed -- Settings > Face ID & Passcode > Attention Aware Features.