Can I keep my Apple ID without transferring old photos to my new phone.

iCloud Photos is a synchronization service. Its purpose is to keep the Photos Libraries on every connected device exactly the same as the iCloud Photos Library. So, as long as a device is connected to an account's iCloud Photos, then it can't a have different set of pictures.

If you turn off iCloud Photos on one device, then its collection of pictures can be different. But then new pictures taken on that device won't go to iCloud Photos and won't be automatically shared with other devices. But you can use AirDrop or texts or other methods to send the new pictures to the connected phones, of course.

Also, if you turn off iCloud Photos can a device, you no longer have the option of using Optimize Storage, so your pictures may take a lot more storage space than they do when you use Optimize. If Optimize Storage is your primary reason for using iCloud, and you want different pictures on different devices, then you would need to have an additional Apple Account.

What do you think?

Beauceronpoodle wrote: …just create a new Apple ID to optimise storage like you suggested!

Running out of storage has few solutions-- get more room or get less stuff, essentially. Optimize can have Photos taking up less than 10% of what they take at iCloud or on a computer. So you might have enough room for all your pictures!

Pictures aren't saved in the "iCloud Backup," and iCloud Photos isn't really a backup, since it backs up mistakes as quickly as it copies pictures. So you should have a plan for backing up your pictures somewhere. Here are some suggestions-- pay attention to backing up to a computer.

Back up iPhone - Apple Support

Turn off iCloud photo syncing, or try restoring from a computer backup.

Change which apps sync and store data with iCloud - Apple Support

Read the support article Transfer data from your previous iOS or iPadOS device to your new iPhone or iPad - Apple Support to learn how to transfer data from your previous iOS device to your new iPhone, iPad, or iPod touch. Select one of the three options: Quickstart, iCloud, or iTunes/Finder.