Try resetting all settings. (Settings - General - Reset)
You'll have to look through the Settings app afterwards and choose everything the way you prefer it again.
If you don't use these features, disable them: Reduce Motion and Reduce Transparency in Settings - General - Accessibility (the latter is in Increase Contrast). Disable features you don't use in Settings. Some of them are turned on by default.
If this doesn't help, back it up, erase all content and settings and restore it using iTunes (although I said before you don't need to do it).
I hope this will help.