Q: How do I add a home phone to favorites in the new iPhone 10 operating system

While in Contacts, open the contact that you wish to add the number to Favorites. From there, scroll down to the bottom of the page. It will have a button for Add to Favorites. Another selection area will appear and you select the number you wish to add.

If you tap on the down arrow next to Call, it will bring up all numbers that are listed in the contact.