Swipe down on the Home Screen and use Search to find the app
If the app is in the App Library, press and hold the app icon, then tap Add to Home Screen
Open the App Store, tap your profile icon, then tap Purchased
Find the hidden app and tap the download icon to reinstall it
Go to Settings, then tap Screen Time
Tap Content & Privacy Restrictions
Tap Allowed Apps or App Store Purchases, then make sure the app is allowed
If the app is hidden from Home Screen pages, press and hold the Home Screen, tap the page dots, then check the hidden page
If the app is in a folder, open the folder and move the app back to the Home Screen
If the app is still missing, restart the iPhone
If needed, sign in with the correct Apple ID in the App Store