Apple’s iOS doesn’t have the best reputation for customization, but with every new iOS version that we get, there are more options to be personalized. Your iPhone is equipped with lots of tweaks and hacks to make this device truly yours, and one of them is a fun but useful mode that adds and turns off icons to activate switches on your iPhone.
On iOS 13 or higher, activating these icons couldn’t be simpler.
Go to Settings -> Accessibility -> Screen & Text Size, then tap the switch next to “On / Off Label.” Now, the deactivated switch will display “I” or “1,” depending on your interpretation, while the deactivated switch will display “O” or “0.” This setting applies to all switches in all Settings applications, but also applies to preferences in all supported applications as well.
Even though these icons don’t really do anything, they serve two purposes. First, they add other visual cues to find out whether an arrangement is on or off. In Apple’s human interface guidelines, it is stated that “adding labels makes it easy to see whether the switch is on or off.” Second, it serves as a pleasant aesthetic choice to turn you off.