The minimum deployment target defines the minimum version of the operation system (iOS in this case) that your app will run on. If your app is targeted for iOS 16.5.1, you will only be able to run your app on devices running iOS 16.5.1 or later (which include your iPhone 8). However, I'm not entirely sure if your computer will work for that because Apple tend to only provide some support for devices whose operating systems are older than those that the computer is running. For example, with your Mac, the latest version of macOS that I believe is supported is the latest version of macOS Monterey (not entirely sure of the number but 12.x.y), while iOS 16 was released around the same time as macOS 13. As such, I think your computer is likely too old to develop for your phone. However, having said that, even if your computer were able to develop for iOS 16.5.1, it would likely not have support for much longer. Usually Macs can last at least five years with future macOS updates, though it can be somewhat unpredictable based on the requirements of a particular software version and the hardware in question.