See full Android Authority article from Oct 2021, or just the extract below.
Greeting Google Assistant before answering a phone call or dismissing an alarm soon won’t be a requirement. The voice assistant is now gaining quick phrases, a feature that will allow users to issue commands without saying, “Hey Google.”
As first detailed in September 2021, quick phrases will allow Assistant to react to commands without the need for a hotword. Notably, XDA-Developers describes how these commands can be as brief as one word to control phone calls or alarms. For instance, users can command “Answer” or “Decline” for incoming phone calls without additional activation prompts. The same goes for alarms. Barking “Snooze” or “Stop” delays or cancels the ringer. Google is reportedly planning several additional commands, too, for controlling music, timers, and smart home items, jotting down notes, and setting reminders.
It’s an excellent addition for those looking for more immediate voice control or in moments when devices are out of reach. Of course, someone shouting “please answer your phone” from across the room may accidentally pick up your call. Mumbling “snooze” while half asleep may not be a great way to get to work on time, either. Essentially, you might want to use quick phrases with discretion.
See also: Essential Google Assistant commands you should know
Those who use “Hey Google” to greet Assistant might also find the new feature jarring. More than three in four readers in a recent poll admitted using “please” and “thank you” in conversations with their voice assistants. Understandably, single-word commands may be a bit too curt for some.
XDA‘s Mishaal Rahman notes that the feature was discovered on a Pixel 3 XL running Android 12 beta, but Google has yet to announce the feature’s availability formally. That said, we can likely expect quick phrases to make its way to more devices in the coming weeks.
19/05/2023
Google Assistant supports Quick Phrases for alarms, timers, and incoming calls. For alarms and timers, you can simply say “stop” or “snooze.” For incoming calls, you can say “answer,” “decline,” or “silence.”
One important thing to note is Quick Phrases are only available on Google Pixel Android devices. Google Assistant-enabled smart speakers and smart displays have a similar feature that doesn’t need to be manually enabled
01/09/2021
Click here to read an article by 9to5Google called "Here’s how Google Assistant’s upcoming ‘Quick phrases’ will let you skip ‘Hey Google’ part of a command" but still let you [by voice recognition for individuals] get things done easier.