Unable to block unsolicited spam calls

Are they all from the same number? My experience with spam calls is they can easily enter a fake number and they have billions of numbers they can use.

Block phone numbers, contacts, and emails on your iPhone, iPad, or iPod touch - Apple Support

Detect and block spam phone calls - Apple Support

Is there a way to just block these kind of computer generated spam calls?

No. If you can find a way you'd be famous. The only way would be to block calls from anybody not on your Contacts list. Even then I'm not sure it would work 100% if the spammer is using a service that allows spoofing caller ID and they used one of your friends' ID.

Or in this day and age somebody has programmed a computer to robo-call every single 9 digit combination of numbers. Unless they do something like start charging a penny for every email sent and a penny for every phone call made we're stuck with it. With free phone calls and email the spammers don't care if only 0.1% of the people they try to contact fall for it.