How to prep iPhone 7plus for data transfer to 14?

The iPhone 7 Plus can be updated to iOS version 15.x.x. Ensure that it is updated to iOS 15 which it supports. You can then follow the instructions for the Quick Start method and here is how to do that 👉  Use Quick Start to transfer data from your previous iOS device to your new iPhone.

Axel F.

Where do you see "The 1st step is to update to iOS 17..."? That isn't a requirement and I don't see any mention of it in any of the3 methods described in Transfer data from your previous iOS or iPadOS device to your new iPhone or iPad - Apple Support

You should have no issue using any of those methods with an iPhone 7 Plus and iOS 15.