Guided Access for “Guest Mode”
Apple’s iOS doesn’t currently have any type of guest mode or privacy-protecting setting for those times when you hand off your device to a friend or family member. But an accessibility setting called Guided Access can mimic that ability.
Enable it in Settings > General > Accessibility > Guided Access. From here, you can input a passcode and select particular buttons or actions to disable. When Guided Access is enabled, you can hand your iPhone off to someone else without any risk of them getting into parts of the system you’d rather them not to.