I'd use the report as spam button instead of just deleting it. I'm not sure it does anything, anyone know what that actually does?
On Android, "Block & report spam" says "The spammer's number and recent texts go to Google and may go to your operator (charges may apply). Learn more: https://support.google.com/messages/answer/9061432?hl=en
for iPhone, it appears there is no native spam blocking function from apple, unless you install a 3rd party app that can check it's own databases: https://support.apple.com/en-ca/HT207099
Reporting it to Google depends on how much you trust google, but when it comes to 3rd party apps, I'm out for sure...