Yesterday, Apple has announced the new update to macOS Big Sur, iPad OS and iOS 14. The iOS 14 developer preview has an additional function to limited 60 fps which hints the next iPhone flagship might be able to support display higher than 60Hz.
If you got to Settings – Accessibility – Motion, you can see an option to limit the maximum frame rate of the display to 60 frames per second (@JunoTecho sent me the screenshot)
— Ben Geskin (@BenGeskin) June 23, 2020
This settings can be found on Settings > Accessibility > Motion and it is named as “Limit Frame Rate”. Once enabled, the refresh rate/ frame rate will be limit to 60fps.
As for the current iPhone 11 Pro Max, the maximum refresh rate is only at 60Hz. This could mean the future of iPhone flagship might have display rate higher than 60Hz, or at 120Hz.