A smaller notch and diagonally aligned cameras on the back.

While were still a good 5-6 months away from Apples next iPhone reveal, rumors about the iPhone 13 have already begun circulating and now leakster David Kowalski (@xleaks7) has teamed up with Coverpigtou.it to share CAD-based renders of the Product Red iPhone 13.
The overall design remains similar to the iPhone 12 series with flat sides, and a notch though the cutout is visible smaller this time around. The dimensions are listed as 146.64×71.5×7.56mm is close if not quite identical to last years iPhone 12.
The big change comes around the back where the two cameras now sit diagonally from each other. The same camera design was seen in yesterdays iPhone 13 mini CAD leak though we sadly dont get info on the actual sensors.
As for specs, the new leak suggests LTPO displays for all iPhone 13 series devices. Display sizes are expected to remain unchanged meaning a 6.1-inch screen for the iPhone 13 and 13 Pro, 5.4-inches for the mini and 6.7-inches for the Pro Max. Apple is expected to bring its new iPhones in October with the range starting at the $700 mark.
Source (in Italian)