How do I block SMS text spam?

I open my Mac's message app (I also get the text on my iPhone, iPad, & Apple Watch), and wish to add this caller to my "blocked" contact, but don't see how to do this. Some of my SMS text spam don't appear to have phone numbers. Maybe "SMS with 9564489646" is something I can add to my contact "blocked" number, but if so, I have to write it down by hand and transcribe it. But it appears that I would need to re-add my "blocked" number to message/preferences/iMessage/blocked every time I make a change.

I pay for "RoboKiller" on my phone, but that just looks at phone calls.

Is there a practical way of marking a SMS text sender as Spam?

I have a Spam 'contact' & just add to that.

I've not figured a good way to do it on my iPhone, but on Mac from the drop menu on the incoming number, Add to contacts… then the Spam contact.

^{I can't add a pic of an actual spam message & procedure, because, of course, I never hear from them again, so this is a 'fake'}