The next major update to Windows 10 is right around the corner, though there are still a few coats of polish Microsoft wants to apply before it goes public. In the meantime, Microsoft is testing a "throttled approach" to its eventual roll out. As such, a small subset of participants in the Windows Insider program can grab the 19H2 release (build 18363.327).
In total, Microsoft is testing the 19H2 update on around 10 percent of Insiders who are subscribed to the Release Preview ring. Those who are eligible can go to Settings > Update & Security > Windows Update to see that a new version (1909) is available to download and install.
In due time, Microsoft will deliver a finalized update to the public using its servicing technology that it uses for monthly updates. The update is not a ginormous one like previous major updates to Windows 10 have been, which makes this a viable route to take.
"We will deliver this feature update in a new way, using servicing technology (like the monthly update process) for customers running the May 2019 Update who choose to update to the new release. In other words, anyone running the May 2019 Update and updating to the new release will have a far faster update experience because the update will install like a monthly update," Microsoft previously explained.
The Windows 19H2 update is going to be more akin to a Service Pack upgrade of old, whereas past bi-annual updates to Windows 10 have been rich on features and new additions. Microsoft appears to be slowing things down a tick, perhaps to better manage these updates and avoid the kinds of issues that plagued the October 2018 Update.
A bigger, more comprehensive update will roll out next year (20H1). As for the 19H2 update, it is currently scheduled to arrive sometime next month.