21 Define Your Triple Click of the Home button
Using the iPhone’s Home button is typically a pretty simple thing. You click it to go Home, and double-click it to open up multitasking. But a wide range of features can actually be mapped to the Home button and activated with a triple-click.
Guided Access, a handy feature, can be mapped to the triple-click along with a slew of Accessibility features. Inverted colors works well for sending iMessages in a movie theater (it’s basically dark mode for your iPhone).
You can enable grayscale, inverted colors, AssistiveTouch and other handy features with a triple-click. To edit your preferences, just go to Settings > General > Accessibility > Accessibility Shortcut.