How do I backup my iphone photos when my phone's memory is larger than my mac?

I have an iPhone 12 (256GB) with 2TB of iCloud storage. I have 519.1GB worth of iphone photos on my iCloud account but want to back them up to an external hard drive so I can delete the photos I don't currently need from my iPhone. I do, however, want to look back at these photos in years to come for memories' sake, so I definitely do NOT want to delete the photos forever!

The problem is I have a 2017 Macbook Pro (121GB) which is way smaller than my phone & so I've never been able to sync my phone to my Mac to back it/my photos up.

Does anyone know a way to resolve this issue? I am so lost

Thank you!