Actually the term may be “pinky ledge”. I think I remembered it wrong. I got the 13 Pro for the same reason your sister did, I liked my 12 mini a lot, but wanted the feature set. The joke was on me because the screen tech on the 13 Pro triggered a migraine problem that rendered me unable to use it, or go back to my 12 mini, so now I’m on an SE3 and an iPhone 11. No OLED for me this year. Sometimes I can use OLED so I’m going to give it another go with a 14 Pro or Pro Max. I haven’t decided yet."pinky bridge" lol Interesting. I don't have a 13 Pro, so I haven't held it very often. My 12 Pro will start to give me discomfort if I'm holding it too long. My sister has a 13 Pro and she is about 5'2" and uses it with no case or grip. I'm about 5'9" with average sized hands. I at least have a pop socket on mine, but she seems to have no issues with it. She wanted the size of the mini, but got the Pro because of the feature set.
I have to use a case. To me these phones are too slippery without one. Impressive that your sister doesn’t use one.