You can use a feature called Guided Access to lock down your iPhone to a single app before you hand it to a kid or someone else. You might want to let your offspring play a game, or pass your phone around for controlling music, or hand it off to show someone a video … but you probably don’t want them going rogue and reading your texts or calling your mom.
In Accessibility settings, you can enable Guided Access to limit your iPhone to a single app before you hand it off. It’s a kind of quick and dirty “guest mode.”
This will help you keep your phone — and your privacy — safe. You can even disable features like the volume buttons and set up time limits.