How do I find path for Messages and WhatsApp messages backup data in iCloud?
iMessage data is not currently accessible via iCloud. This will be coming in macOS 10.13/iOS 11. You can currently only restore files from iCloud Drive, contacts, calendars/reminders and bookmarks, all from the Advanced section in iCloud.

WhatsApp messages can be restored from Google Drive if you turned this feature on.

Alternatively, if you turned on the device backup for iOS, either to you local Mac/PC or to iCloud, you could do a full restore to get your data back.