https://wccftech.com/2020-iphone-promotion-display-will-support-120hz-refresh-rate/

A new report claims that 2020 iPhone will ship with 120Hz refresh rate ProMotion OLED display. This will result in a smoother user experience, similar to what iPad Pro's ProMotion LCD display already offers. Along with 5G and new design, a high refresh rate display means that 2020 iPhone will have a huge list of new features.

ProMotion is the name of Apple's technology which not only supports a high refresh rate, it also smartly adjusts the refresh rate based on what is displayed on the screen. Gestures like scrolling and swiping, as well as other animations look far better on a ProMotion display, compared to a 60Hz only display.