This sends a signal to the sender and the carrier that you didn’t want it.
Next, look for the messaging app feature to “Block and Report”. This sends a signal to Apple/Google and possibly others that the message was spam.
Now, I do these things and I continue to get political fundraising pleas over text from groups I don’t recognize.
BUT, I also work with bulk emailing and know it takes a very small number of reports, less than 1%, of messages reported as spam before the bulk-mailer/carrier blocks and penalizes the group originating the message.
I think some collective action here by a small group can make a difference.
In regards to iOS, if you reply you cannot then select "block and report spam" (or if you can it's not a swipe action like it was previously). So I just block and report spam for every one that comes in.