Google Assistant is available for phones running
Android 6.0 and later. Before you can say "OK Google" to launch
Google Assistant, you need to set it up and teach it to recognize your voice. To set up
Google Assistant, connect your phone to the Internet and then press and hold HOME /Fingerprint scanner.
Google Assistant to respond to "OK Google" and voice commands, Battery saver in
Settings must be turned off.
To check if Battery saver is turned off: