Now that new iPhones from the iPhone 15 have USB-C it makes it a lot easier to copy files to and from the iPhone. This means you can connect memory sticks and external drives. I often connect a card reader so that I can copy photos I’ve just taken directly to my iPhone, it then also saves it to the iCloud. If you are going to do that just be aware of your data allowance, you don’t want to be using it all up.
Once I’ve copied these files I can then send them or even load them into an app like Lightroom where I can edit my files.
You can also copy files from your iPhone so that you can save space or use them on another device.
This has been something you’ve been able to do for a while with iPads that have USB-C so you can do that there too.
All this makes using your iPhone even more useful.