Transferring my pictures to external hard drive

Hi! My iPhone is full with 6000+ pictures and videos. Too much I know! And I have to do something about it. I tried to connect my phone to my MacBook Pro but I could only reach the latest 1200 pictures. After some research I realized that the rest of my library is optimized to take less space on iCloud. To access this pictures I thought that I could turn off iCloud photos in my phone, but I get a warning that if I do so, my pictures will be deleted on the phone, but I can still reach them online.

So I thought I could just log into my computer, iCloud and then transfer all my pictures to my computer and then my external hard drive. But this is not working either! I don’t have enough space on my MacBook to store the pictures before transferring them to the hard drive. When I press the “download picture” button on iCloud, I can’t choose to download it to my hard drive, only MacBook. What am I supposed to doooo

English isn’t My first language so I’m sorry if I don’t make much sense! But please try and help me.😅