Reduce or stop the motion of screen elements on iPhone
If you have sensitivity to motion effects or screen movement on your iPhone, you can stop or reduce the movement of some screen elements, such as:
Parallax effect of wallpaper, apps, and alerts
Animated effects in Messages
Go to Settings > Accessibility > Motion.
Turn on or off any of the following controls:
Reduce Motion: This setting reduces the motion of the user interface, including the parallax effect of icons.
Prefer Cross-Fade Transitions: This setting reduces the motion of user interface controls that slide in and out when appearing and disappearing.
Auto-Play Message Effects: This setting allows the Messages app to automatically play full-screen effects. If you turn this setting off, you can still manually play effects by tapping Replay below the message bubble.
Auto-Play Video Previews: This setting allows apps such as the App Store to automatically play video previews.