How can I see all my iCloud photos?

If you have iCloud Photos turned on, the photos on the device are the same as on iCloud, with the possible exception that some of them may be space-saving optimized versions if you have that option turned on. You view them in the Photos app on an iOS device. You can also login to icloud.com and go to the Photos app there. See: https://support.apple.com/en-us/HT204264

If you didn't have iCloud Photos turned on but do have an iCloud backup, you can restore the entire phone (not just the photos) from iCloud but you cannot otherwise view the contents of the backup. https://support.apple.com/kb/ph12521

iCloud is a syncing service, so if you have iCloud photos turned on in Settings->Photos, then any photos in the Photos app are by definition in iCloud.

If you need to verify, you can log in to the https://icloud.com website with your Apple ID, and use the photos web app there to view all photos synced to icloud.

how can i see all my photos stored on icloud