The way Apple works is that they’ll introduce a new feature for its higher-end iPhones first, and then the following year, that feature is expected to be available across the board. This is kind of like how Apple approached OIS for the iPhone cameras and also the use of OLED displays for the iPhones as well.
However, it seems that might not happen with the ProMotion 120Hz display. According to a report from South Korean publication TheElec, not all of the 2022 iPhone models are expected to come with a 120Hz display that Apple introduced to its iPhone 13 Pro models this year.
This is because the publication claims that out of the four iPhone 14 models rumored for 2022, Apple will apparently still be using an LTPS OLED display for one of them, not LTPO which is needed for the higher fresh rates. Presumably the use of the LTPS display might be for the lowest end model, but it might be too early to tell.
It’s interesting that the report claims that there will be four models. This is because it has been rumored that this year will be the last year we’ll be seeing the “mini” iPhone, so claims of four models would either suggest the rumors are wrong, or Apple could have another model they plan to replace the mini with.