Every Mac comes standard with assistive technologies that can help you use macOS.
macOS features an Accessibility Options window that lets you quickly turn on or off common accessibility features like Zoom, VoiceOver, Sticky Keys, and more. You can bring up this window anytime with a simple shortcut.
- On the built-in keyboard of a Mac notebook computer, press Fn-Option-Command-F5.
- On a Mac notebook with Touch ID (power button),* triple-press Touch ID.
- On an external keyboard, press Option-Command-F5.
If you accidentally activate the Accessibility Options window, click Done to close it, or click anywhere outside of the window.
*MacBook Pro (15-inch, 2016), MacBook Pro (13-inch, 2016, Four Thunderbolt 3 Ports)
Use Siri
If you have macOS Sierra, you can ask Siri to turn accessibility features on and off.
Click the Siri icon 
in the menu bar or Dock. Siri asks "What can I help you with?" You can ask Siri to do things like "turn VoiceOver on."
You can also hold down both the Command (⌘) key and Space bar until Siri asks, "What can I help you with?"