I have returned the iPhone 3GS twice, due to the cracks on the back cover, on the white model. It was a typical fault on the white model. Then I have returned 2 black iPhone 5 due to chips on the edges, also a classic. Then I have returned an iPhone 6S, because the screen did not fit tightly in one corner, and then I have returned an iPhone 8, because it had a large scratch at the lightning port. The iPhone 13 Pro is the last one I returned because it wouldn't turn on at all. In addition, I have returned an iPad Air 3 because the Home button was "crispy" and stuck a little when pressed.
So in total I have returned 7 iPhones and 1 iPad.
Where I come from, the iPhone cannot be returned once the seal is broken, unless the phone is damaged. I often read in here that people can return their iPhone if they regret, for example, the color - is this normal in the US?