https://www.techradar.com/news/all-2019-iphones-could-have-oled-screens

In 2019 Apple could complete its transition to OLED, as a new report claims that all three 2019 iPhones will have an OLED display.

Right now Apple only uses OLED on one iPhone - the iPhone X - and most rumors suggest that of the three suspected iPhone models launching this year, two will get OLED screens, while one will stick with LCD.