Purchased two seemingly identical iphone 13 Pro about two months apart. The most recent purchase had smaller side buttons and was unable to obtain the same display brightness with same options selected in settings. Suspect one phone may not be a true Apple device?
My mistake. The brightness problem was different under "accessibility" while the same under "display brightness" . Turned off "auto brightness" and now the two displays are the same.
Side buttons are also the same. Costco put different Pelican casings which made the side buttons seem different. The smaller casing buttons are better because you don't tend to turn the phone on accidently. Hope this explains my mistake.