In context: Nobody likes spam calls, and that's something the US government and tech giants understand. The former is working on various pieces of legislation to counter "robocalls," and both cellular providers and phonemakers have developed tools to block the calls from coming in at all.
Google is one such company. In 2018, it rolled out a beta version of its "Call Screen" tool, which, as the name suggests, can automatically screen calls for you. Since then, Call Screen has become a finished feature that lets Google Assistant pick up the phone for you and ask who's calling and why.
If it determines that the call is spam, Assistant will hang up the phone. If it feels the call is legitimate, your phone will ring, and you'll see a live transcript of how the caller responded to Assistant's first questions. At that point, you can choose to answer or ignore the call.
To date, automated Call Screen functionality has only been available on the $800 Pixel 4, but new reports claim the feature has come to the Pixel 1, 2 and 3 as well. This falls in line with Google's previously-announced intentions to bring Call Screen to its entire family of smartphones.
If you don't have a Pixel device, you can still use Call Screen, but only in manual mode, and only on an Android device. In this case, manual mode just means you'll have to do a bit more of the heavy lifting -- Assistant will still ask who the caller is and give you a live transcript of their response, but you have to hit the "Screen call" option for that to occur. You'll also have to decide whether or not the call is spam for yourself; Assistant won't automatically hang up for you.
For more details on how Call Screen works, as well as instructions on how to set it up, visit Google's Phone app help page right here.