How can I copy photos from my iPhone onto my Mac, not transfer

Transfer photos and videos from your iPhone, iPad, or iPod touch to your Mac or PC - Apple Support

You can connect your phone directly to your Mac or use iCloud.

There is AirDrop. You may also email images to yourself..

And an extra email account may give you a buffer & help

save some in between, such as google photos can allow.

System software included in macOS &/or iOS, work two ways.

Some items in 'Continuity' are almost automatic, once known.

You don't have to lose the images from your Phone. NO matter how you get there, deleting the images from the phone is always an optional step.