Do not go gentle into that spam SMS.
Filter SMS and MMS from unknown senders into a separate, muted list, called Junk. Mehssages SMS filter extension turns off notifications for SMS and MMS from the numbers which are not in your Contacts.
Make Allowlist by senders phone number or body text to receive messages normally.
Use Mehssages’ Messages app to add an item to the Allowlist or paste a phone number from your clipboard.