If any 13 mini users are holding on to them because they were apprehensive/didn't like the larger 'Pro' size...
Worry not.
I was in the same boat. I always bought the smallest iPhone. I was fine with most of the earlier iPhones, but was most comfortable with the 12 mini and 13 mini. The 'Pro' phones always felt too big and heavy and bulky.
I thought I'd try the 15 Pro for a change, and it's been great. Honestly the adjustment hasn't been an issue at all - this is mainly due to how light the 15 Pro is compared to previous 'Pro' phones. Yes it's still a little heavier that the mini but I promise you'll get used to it. The 14 Pro was too heavy for me, but the 15 Pro is just right.
So if you're sat on the fence, go for it.