How to backup photos
Buy another device from apple
iPhone 14 Pro Max, iOS 18
Question marked as
Probably the best way to backup pictures on an iPhone is to plug in an external drive, select the pictures you want to save, and choose Share>Save to Files. You will get a dialog window that will allow you to navigate to a folder on the external drive. This will save the edited and cropped version of your pictures.
You should also save the Original, unedited versions. For that you choose Share>Export Unmodified Originals.
Then store the drive in a safe place.
I'm not sure what you mean by "Buy another device from apple" or its relevance. If you want to buy a hard drive from Apple, here's one:
LaCie 2TB Rugged USB-C Portable Hard Drive - Apple
But the same drive is cheaper at Amazon-- especially with their Black Friday sales.