How do I save photos on I cloud but erase on iPhone storage to free up space
How do I free up space on my I phone storage. I have I cloud . When I erase pics from my photos on my phone it erases it from I cloud as well.
iPhone XR, iOS 13
You can potentially reduce the storage space required on a device by turning on Optimize Storage. See: Set up and use iCloud Photos - Apple Support
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.
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.