How to disable video previews playing automatically in iOS 14 for iPhone/iPad/iPod Touch

Open the Settings app . Note: The Settings app icon may appear in a different place on your home screen than shown in our example, below.
In the Settings app, scroll down and select Accessibility from the list.
On the Accessibility screen, select Motion.
On the Motion screen, select Auto-Play Video Previews to set the toggle switch to Off.
When you are happy with your settings, you can return to the home screen page of apps by:
- On devices with Face ID: Swipe up from the bottom of the screen.
- On all other devices: Press the home button once.