Can I get my photos from an old existing iCloud account?

https://discussions.apple.com/thread/250656024

Note : the iCloud server will never delete the photos , whether you don't sign in for months in an old account , the basic conditions are the photo box must be always checked in , the data should be in designated limits .

https://support.apple.com/en-in/HT204570

Are the photos from this old account still in iCloud?

You can check this by signing into the iCloud account with the AppleID and password. Use a web browser on a computer and open www.icloud.com. Sign in with old AppleID, then open the Photos.app there.

Are the photos still there? If an AppleID has not been used for a long time and you have not signed into this account from an AppleDevice for more than six months, Apple may have removed the photos.