My phone has an option called Do Not Disturb mode. I have set a schedule to turn it on everyday from 12AM to 11:59PM. What Do Not Disturb will do is block (silence the notification or ringer) every message or call from someone that is not in your phone book. While unfortunately you'll still get the spam SMS, but you wont get the alert.
The only way I can see striking back at these spam calls is to pick up the call and waste their time, because its expensive. Also if I pick up that means someone else is not getting scammed. I try to get as far along in the scam process as possible.
I enjoy the pixel line of phones having google assistant answer spam calls for me. Sometimes its fun to watch the conversation they attempt to have with the assistant.
This isn't just pixel phones anymore, and it hasn't been for a while. You can also tell that it's not a person sometimes (specifically extended car warranty for me) if you have a cheap phone like mine, because you can hear the message on the other end start as soon as the line opens, before the phone shuts off the speaker and starts playing it's own message; once the assistant finishes talking, you can see the transcript start in the middle because the other end doesn't recognize Google assistant like it (probably) would an answering machine.
At least here human operators apparently are paid for call duration and they will prolong the call up to 15 minutes and you don't need to say anything.
The only way I can see striking back at these spam calls is to pick up the call and waste their time, because its expensive. Also if I pick up that means someone else is not getting scammed. I try to get as far along in the scam process as possible.