Tip: If you have visual impairments, you can enable additional magnification 
gestures.
Pinch in to zoom
Put two fingers on the screen, far apart, and then drag them together.
Result: Zoom out to see smaller version of photos or maps. Or, close expandable 
notifications.
Use gestures with Power button
Press 
Lock and unlock the phone. You'll enter your PIN, pattern or password to unlock. To turn off the phone, 
press the Power + Volume up buttons simultaneously.
Press twice 
Open the camera. If this doesn’t work, check that the setting is turned on.
Press & hold 
Start a voice command with Google Assistant.
Learn the basics : Get around on your phone 29