https://wccftech.com/apple-to-use-iphone-13-name-in-2021/

Even though multiple reports mentioned the iPhone 13 name, some information coming out of the woodwork suggested that Apple could use iPhone 12S instead since the upcoming lineup served more as an iterative update. However, fresh details claim that the technology giant is expected to stick with the number '13' and the names used to differentiate last year's iPhone 12 line.

Citing sources close to Apple’s plans, coupled with supply chain checks, Apple is expected to name the upcoming series the iPhone 13. Before the end of 2020, it was reported that the company would unveil four new models in the coming year, with all four of them sporting the same display size and design as the iPhone 12 series. With Apple sticking with the same screen sizes, it is not a surprise that it will name the forthcoming devices the iPhone 13 mini, iPhone 13 Pro, and iPhone 13 Pro Max.