How do I retrieve iCloud password when I am not receiving an email?

If you are not receiving mail in iPhone If you can't receive email on your iPhone, iPad, or iPod touch - Apple Support

The Apple ID password can only be reset If you forgot your Apple ID password - Apple Support

If you are using a Mac and not getting mails in iCloud.com If iCloud Mail isn't working - Apple Support

If you have trouble receiving email in Mail on iCloud.com - Apple Support

Check available email storage in iCloud - Apple Support

If your iCloud mailbox is full - Apple Support

The Apple ID password can be retrieved if iCloud Keychain is set up in Mac Set up iCloud Keychain - Apple Support

From keychain access by an administrator only View the information stored in a keychain on Mac - Apple Support