I installed the "Bouncer" ios app a few months ago and it has been pretty good.
Just added a bunch of keywords to the junk list like "trump" "biden" "actblue" "winred" etc. Only applies them to unknown senders so its not like I will miss texts from friends that happen to contain those words.
I must be on some list because I get a LOT of donation requests from candidates in random states I've never even been to...so I have to occasionally add new terms to the filter list, but otherwise it works pretty well.
It has filtered 204 texts since October 31st...