2 factor identification
Can I turn on 2 factor authentication for my iphone only
Question marked as
Two-Factor Authentication is not tied to a specific device. It's tied to your Apple ID.
When you turn it on, all devices using that Apple ID become trusted devices and will get the 2-Factor Authentication code when one of them requests it or when you add a new device to your account or log in to an Apple service with your Apple ID from a non trusted device or web browser.