Apple recommends in their guidelines a minimum tappable area size of 44x44 points for all controls. A lot of times this can be corrected in an app without changing how it looks, but making it objectively easier to interact with for everyone.
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If you have any web views in your app (Terms and Conditions and Privacy Policy, I'm looking at you), you can also support Dynamic Type for them. You can set an Apple system font with the same styles available for native development in your CSS.
Anything representing a heading in the app should have the header trait. It allows for a faster way of exploring a screen and jumping to the part of the app you are interested in. Screens should also start with a header.
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