Copying photos from iPhone

Another possibility is Image Capture.

Transfer images in Image Capture on Mac - Apple Support

iCloud Photos is the most convenient way – if you have enough storage space on iCloud, and on each device (iPhone, Mac). You add photos on one device, and they show up on the other.

Hello,

iCloud Photos...

Set up and use iCloud Photos - Apple Support

In the Finder also...

Sync your photos using the Finder – Apple Support (UK)

If you are worried about losing photos in iCloud you can enable iCloud and install Amazon Photos and Google Photos on your iPhone, these can be set to synchronise your photos so you will have three independent copies of your photos. When you install these on your iMac you can access the photos from there too. I do this and it works seamlessly.