can’t recover photos from icloud

See this article https://support.apple.com/en-in/HT204264

Before you begin

1. Update your iPhone, iPad, or iPod touch to the latest iOS, your Mac to the latest macOS, and your Apple TV 4K and Apple TV HD to the latest tvOS.
2. Set up iCloud on all of your devices.
3. Make sure that you’re signed in to iCloud with the same Apple ID on all of your devices that you want to use with iCloud Photos.

https://support.apple.com/library/content/dam/edam/applecare/images/en_US/mac_apps/itunes/divider.png

Turn on iCloud Photos

• On your iPhone, iPad, or iPod touch with iOS 10.3 or later, go to Settings > [your name] > iCloud > Photos, then turn on iCloud Photos.

In case if photos box was not turned on that photos will not be saved / synced with the iCloud server , also if you delete photos from iphone they will be deleted from iCloud server and will be moved to recently deleted folder in iPhone as well in www.icloud.com and will be kept only for 30 days after the time period they will be automatically deleted , and suppose you delete all the photos immediately and permanently they will be gone forever see this article https://support.apple.com/en-in/HT205856

some options are in details to recover back the photos .