Like IPhone 11, but with a decidedly flat-edged chassis, as opposed to a round-edged one, with the colored finish of the phone clearly bordering the display from the front.
Visually identical to iPhone 12 mini.
If the two cameras on the back are arranged diagonally instead of vertically, it's IPhone 13.
If there are three cameras on the back, use IPhone 12 Pro instead.
Distinguishing from other models when only the front is visible
If the finish is typically white, black, blue, green, purple, or red, it's likely IPhone 12.
If the finish is graphite, silver, gold, or pacific blue, it's likely IPhone 12 Pro.
If there is no colored trim and the edges seem rounded, use IPhone X instead.
