Deleted apple apps by accident

Apps can be removed from the home screen without being deleted. Go to the App Library (swipe left past your last home screen). From there you can touch and hold an app and slide it left back to the home screen.

If the app was deleted (i.e., is not in the App Library, you can reinstall it. See the following from Delete built-in Apple apps from the Home Screen on your iOS 14 or later or iPadOS device or Apple Watch - Apple Support

Restore a built-in app that you deleted

1. On your iOS or iPadOS device, go to the App Store.
2. Search for the app. Make sure that you use the exact name of the app.
3. Tap 

A cloud with an arrow pointing down from within the cloud.

to restore the app.

Wait for the app to restore, then open it from your Home Screen.

Go to the App Library (the last page of the Home screen), hold your finger on it and drag it back to where you want it.