It is possible to hide apps on iPhones in multiple ways. For example, you can organize them in folders or place them in your app library. When you have iOS 14 or later installed, you can also remove all home screen pages in order to reduce clutter on your home screen.
Suppose you need to locate an app you haven’t used for a while and don’t remember how to access it. There may be hidden apps on someone else’s phone that you need to check. Learn here: https://www.soldrit.com/blog/how-to-open-hidden-apps-on-iphone/