I wonder is there any app that allows us to record the device screen itself. I am kinda new to iOS. So if anyone knows anything about this kind of an app please can you suggest to me?
There's no need for an app. The capability of screen recording is built into iOS 11 and later.
Go to Settings>Control Center>Customize Controls and add Screen Recording to the list included in Control Center. Here are the instructions for creating a screen recording. How to record the screen on your iPhone, iPad, or iPod touch
Your screen recording can be found in the Photos app.