As you know, every 6 months a new build of Windows 10 is being released.
Well, the latest one – 21H1 – is now available for download from MSDN, Volume License or the download center (https://www.microsoft.com/en-us/software-download/windows10) from which you can get an ISO or create a bootable USB.
The good news is the upgrade process is supposed to take less time as 21H1 shares the same core components than 2004 and 20H2; the expected upgrade time is close to the monthly Windows Update.
If your device update management is managed with SCCM with Software Update or WSUS and have installed the latest Windows Updates (May 2021), you will be able to get the enablement package to upgrade directly from WSUS.
For administrators, there is no update for the Windows Assessment and Deployment Kit (ADK) or Windows PE add-on if you have already installed the 2004 version.