One of IOS's many great accessibility features is zoom.
You can activate and deactivate it by double tapping with 3 fingers. Apps that seem to be built with Apple's UIKit handle this well, but I often accidentally activate buttons or perform other unwanted actions in apps that use some other UI library. This is also the case in games, where I like to zoom in to read small text, or see game elements in more detail.
I understand that accessibility isn't always the most exciting part to work on, especially in games, but it really makes a difference!