Go to Settings > General > Accessibility > Guided Access.Guided Access keeps your iPhone in a single app, and lets you control which features are available.
The feature has to do with an accessibility tool called Guided Access. The example they gave was people who are at a house party, playing music on their iPhone, and don’t want other people to pick up their phone and snoop through it. It’s possible to “lock” your iPhone so it only shows the current app that’s open. Credit where it’s due: Redditor u/MarcDiakiese found an awesome tip for iPhone users.
