How to reduce blue light intensity on iPhone/iPad/iPod Touch iOS

The blue light that makes your screen more easily visible during the day may contribute to poor sleep when used late into the evening. The Night Shift feature reduces blue light and increases the warmer, redder colours.

Magnify objects around you with iPod touch - Apple Support (GE)

How to Adjust Screen Color Tone on iPhone, iPad Running iOS 10

Sick of Yellow Links in Notes? Make Them Any Color You Want with These Hidden iPhone, iPad, and Mac Settings « iOS & iPhone :: Gadget Hacks

How to Use the iPhone Blue Light Filter and Get Better Sleep

Adjust the screen brightness and color on iPhone - Apple Support

Track your menstrual cycle in Health on iPod touch - Apple Support (SG)

How to use guided access in iOS 12 for iPhone/iPad/iPod Touch

How to reduce the intensity of blue light in iOS 15 on your iPhone, iPad, or iPod Touch

Edit portraits on iPhone - Apple Support

What sleep improvement apps for iOS filter blue light and don't require jailbreaking? - Quora