Q: How can I block incoming email from to my IPhone?

Hi Rschine,

I'm not seeing where the web based iCloud Mail rules would apply to the Mail app on your iPhone.  I am wondering however if the junk mail filtering will work for you.

iCloud: Identifying and filtering junk mail - Apple Support

You can also use the Mail app to mark messages as junk so that later messages from the same sender are automatically marked as junk:
•  In iOS 7 or later, open the message, tap the flag icon at the bottom, then tap “Move to Junk”.

 

Take care