HUGE Increase in Spam Text Messages

Are these iMessages, or SMS? The iMessages you will find they are spoofing numbers, so you are going to find that blocking does not work well. SMS, you can report these to your carrier, as they cannot be blocked by the iPhone. They have to be blocked by the carrier.

Like the rest of use, these spammers are stuck at home too, and they are using this time to perfect their annoyance of we normal folks.

I've not received any iMessage spam but I know exactly what you are referring to with the SMS where the To field is consecutive phone numbers. Those are outside the purview of Apple, you need to contact your cell provider and see what tools they have available to help you.

Apple has no control over this.

For SMS messages, if you're in the U.S., you can forward the message to 7726 (it spells SPAM). Your carrier may ask you for additional information. This, at least, will provide the carriers with information on dealing with that spammer.

For group messages, mute the group. Go to the main conversation screen. Find the offending conversation. Put your finger on it and pull to the left. Tap "Hide Alerts".