Hi,
As far as I know there doesn't exist a list of all updates for a specific operating system version.
What you can do is to use search terms which will filter the updates found in the Microsoft Update Catalog.
For all updates that are available for Windows Server 2016, simply search for "Windows Server 2016" in the Microsoft Update Catalog page as follows:
https://www.catalog.update.microsoft.com/Search.aspx?q=windows+server+2016
(If the reply was helpful please don't forget to accept as answer, thank you)
Best regards,
Leon