This will become available via Windows Update for Windows 10 1909 and 1903 with the “Check for Updates” option … Also it is more immediately available via the Windows 10 Software Download Center (Update Now and Media Creation Tool) which can help force updating sooner if desired

https://blogs.windows.com/windowsexperience/2020/05/27/how-to-get-the-windows-10-may-2020-update/

https://www.microsoft.com/en-us/software-download/windows10

For information about the latest features for commercial customers, see “What’s new for IT pros in Windows 10, version 2004.” For insights on how to update, see the Windows IT Pro Blog post on feature updates while working remote. If you’re curious about Windows Server, version 2004, which was also released today, see the Windows Server Containers blog.