iPhone storage

Do you have the Optimize iPhone Storage option turned on? See the following from: Set up and use iCloud Photos - Apple Support

iCloud Photos keeps all your photos and videos in their original, high-resolution version. You can save space on your device when you turn on Optimize Storage.

On your iPhone, iPad, or iPod touch:

1. Go to Settings > [your name] > iCloud.
2. Tap Photos.
3. Choose Optimize [device] Storage.

and

If you turn on Optimize Storage, iCloud Photos automatically manages the size of your library on your device. Your original photos and videos are stored in iCloud and space-saving versions are kept on your device. Your library is optimized only when you need space, starting with the photos and videos you access least. You can download the original photos and videos over Wi-Fi or cellular when you need them. You can use Optimize Storage on your iPhone, iPad, iPod touch, and Mac.

re: "If all your photos are in iCloud, then just delete them from your iPhone. "

iCloud Photos is a syncing service. Any photo you delete from a device where iCloud Photos is turned on will also be deleted from iCloud and from any other device connected to iCloud Photos. You can potentially reduce the storage space required on a device by turning on Optimize Storage. See: https://support.apple.com/en-us/HT204264

Apple does not currently offer cloud-only storage for photos. If that is what you want or need, you may want to explore 3rd party options such as Google Photos or Dropbox.

BeckSim Said:

"iPhone Storage: Hi, i have just got a new iPhone 11 and my photos (4000 wish) which are all on the iCloud are taking 12gb of storage on the phone?"

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Will this Meet your Needs?:

If all your photos are in iCloud, then just delete them from your iPhone. Use a Flash Drive, to store all the photos in for safe keeping, if you do not trust iCloud.

Trying to think of another way to put it:

If you don't always need access to the photos, then store them in a flash drive and then add them back for access when need be ---- an ultimate workaround to the consumption issue presented by the OP.

Right. I think I knew what you were trying to say in the original but thought the wording could lead to loss of photos and wanted to make sure the OP understood.