When you are making videos where you demonstrate something or you want to show an app you're using, you can film the phone and show the audience, or you can actually make a recording of your screen. It's very simple to do with your iPhone, but the feature is a bit hidden, so let me explain how you can do this.
Go to Settings > Control Center > Customize Controls, then tap the Plus sign next to Screen Recording.
Swipe up from the bottom edge of any screen. On iPhone X or later or iPad with iOS 12 or later, or iPadOS, swipe down from the upper-right corner of the screen.
Press deeply on the Circle icon and tap Microphone.
Tap Start Recording, then wait for the three-second countdown.
Open Control Center and tap . Or tap the red status bar at the top of your screen and tap Stop.
To view your recording, go to the Photos app.
This also works on iPad.
Now that you've changed your setting it will always be in the menu and recording your screen will be a piece of cake.
So anytime you want to demonstrate something or even when you just want some B-roll footage of something that somebody is watching on their phone, instead of filming the phone try recording the screen. Using what is going on on the phone as a picture in picture to explain something or have a better understanding of what is going on on the phone is a great way to enhance your video or the story you are trying to tell.