As of my last update in April 2023, there has been no official release from Microsoft of a Windows 9 operating system. Microsoft's release sequence has included Windows 7, Windows 8, Windows 8.1, Windows 10, Windows 11, and so on. However, for the sake of addressing your query, this report aims to provide guidance on how one might approach verifying and downloading an ISO file for any hypothetical or unofficial Windows 9 version.
Microsoft wanted to signal a massive leap forward from the unpopular Windows 8. Jumping to "10" made the software feel significantly newer and more advanced. What Are the "Windows 9 ISOs" Found Online?
The short answer is . Microsoft never publicly released a product called Windows 9.