Google Pixel 4 XL
Turning call waiting on or off
When call waiting is turned on, you can answer a new call without ending your ongoing call.
Press the phone icon.
Press the menu icon.
Press Settings.
Press Calls.
Press Additional settings.
Press the indicator next to "Call waiting" to turn the function on or off.
Slide your finger upwards starting from the bottom of the screen to return to the home screen.