Google has slowly been rolling out a conversation across its smart home devices. Assistant-equipped displays "OK Google" for every consecutive command in March. Phone Phone
Right: Previous versions without the Phone entry. Left:
Since the setting has been published in the Google app for a
The toggle appears to be part of an A / B test, so it can take some time until it shows up for you. It may help with the beta version of the Google app, which you can sign up for on the Play Store or download over at APK Mirror.