Thank you for many detailed suggestions!
Unfortunately, none of your suggestions respond to my request. And, none of your suggestions will do anything to reduce the spam I receive.
For any of your suggestions to work, spammers would need to be honest users that consistently use the same email address, with the same alias, on every email they send. But in the real world, spammers change their address 5 times an hour, every hour, forever!
The ONLY effective solution to spam will be for the IOS email app to offer an option to route email from any address not in my contacts to the junk folder.
My request was and is for a method to route email from any sender not in my contacts to a folder of my choice, such as junk. If Apple does not wish to add this feature, I am willing to install a reliable, non advertising, 3rd party product on my iPhone if someone will recommend one.
Or, if there is a way I can write a rule within IOS to allow me to move any email from any sender not in my contacts to a folder other than my inbox, please provide an example of such a rule.