If you're trying to figure out how to access hidden apps on iPhone, just check the App Library or use the Search bar to reveal any app that's been tucked away. Hidden apps aren't deleted — they're simply organized out of sight.
For revealing concealed applications on an iPhone, first, swipe left until you are at the end of all your Home screen pages and then navigate to the App Library to find the "Hidden" folder. Click on the "Hidden" folder and use Face ID, Touch ID, or passcode to unlock it and see your concealed applications.