Icloud Photo Sharing
2 phones are sharing the same icloud account with icloud photos on. Let’s say one phone took some pictures, then delete them soon (on the Recentlt Deleted tabs too). Would the 2nd phone have the deleted pics in its camera roll?
Question marked as
Top-ranking reply
They would be deleted from iCloud and from every device using the same Apple ID that has iCloud Photos turned on.
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: Set up and use iCloud Photos - Apple Support
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.