Hi, my name is Anis. I'm an Independent Advisor and a Microsoft user like you. I'll be glad to help you today.
Unfortunately you can only download the latest version of Windows 11 from official Microsoft website.
However, you can download the older version of Windows 11 (21H2) from Archive.org. It's a third party website but, it's considered pretty safe.
You can actually find any file published by any organization on Archive.
Here is the link:
https://archive.org/details/Win11_English_x64
Note: Although it is safe do download from Archive, but please note that archive is a third party website with no association with Microsoft whatsoever.