In addition to features that attract attention like the dark mode and computer mice that contains iOS 13, Apple has also made its mobile platform more user-friendly for people who are sensitive to animations on the screen. If you've always found the transition effects between app pages, your iPhone now has a setting to help you prevent potential motion sickness and anxiety.
The traditional gliding animations give your iPhone a more natural feel as you move from one page to another while browsing an app. However, the pleasant experience is not universal for everyone. According to Apple, one in three users suffers from motion sensitivity in one form or another, with on-screen animations a potential source of discomfort for a smaller subset.
To help individuals who are physically and mentally upset by the sliding transitions, as well as for those of us who prefer a different animation for adaptability, there is now a cross-fade for smoother transitions from page to page. The option can be found on the "Motion" page in the "Accessibility" menu in Settings, although you must first enable "Reduce motion" to see it.