Filter your text messages for keywords, have blocked ones sent to the spam filter, and allowed keywords go direct to inbox (ignoring blocked keywords in same messages). There is no AI or Smarts to this app, everything stays on your phone, all it does is look for the keywords you specify and blocks or allows the messages (by block, move to junk folder). This app is not 'pretty', but was designed because the developer was paying a subscription for an app or two that did the exact same thing, meanwhile there is no need to pay subscriptions with my app. We start by blocking NO keywords, you add them yourself for them to be blocked. Make sure you go to Settings-:>Messages and enable this app as a message filter under blocked/junk messages.

In the author's case, he inherited the phone number from someone who was politically active, so he (i) got a lot of SPAMMY political text messages (most likely were not real), so what was done was to put keywords relating to political figures into the blocker and the messages were being blocked when tested with this app. Some fine tuning (adding/removing keywords) may be necessary until you get it right.