https://www.theverge.com/2018/10/19/18001460/google-pixel-3-xl-google-assistant-voice-match-removed

Google has quietly removed the Unlock with Voice Match function from its latest Pixel 3 and Pixel 3 XL phones, as first reported by Piunikaweb. The feature, which was previously available on the past two Pixel devices, allowed for users to unlock their phones’ Assistant features with an, “OK Google” command. Google confirmed that the feature is no longer available on its support page, where it explains: “On Pixel 3 phones, you can’t unlock your phone by saying ‘Ok Google.’ Instead, you can use the Google Assistant on your lock screen.”

This is a pretty big functionality to lose for any Pixel owners who were expecting to see the feature carried over to the Pixel 3. With the previous Pixel phones, users could make calls, send messages, and access third-party apps via Google Assistant voice support without unlocking their phones. The “Unlock with Voice Match” toggle in the Pixel 2’s Assistant settings has now been replaced on the Pixel 3’s settings with a “Lock screen personal results” toggle, which now reads “Use Voice Match to access personal results like email, calendar, contacts, and reminders when your phone is locked.”