As is typically the case on the Tuesday after a new Windows 10 Insider Preview build is released, Microsoft released Windows 10 SDK Insider Preview build 18327 today. The build number is a bit lower than last week's Fast ring build, which was 18329.
Once again, Microsoft hasn't published a blog post at the same time that the SDK was released, but it's safe to assume that there isn't anything major that's new. The last few SDKs haven't had anything new, and we're in the final stretch of Windows 10 19H1 development. The new features that we've seen so far have to do with Message Compiler and Fluent Design.
The SDK can most likely only be installed on machines with a Windows Insider Preview, and you can run it side-by-side with existing SDKs in a production environment, as long as your app still targets a production version of Windows when you submit it to the Store. Also, it's only officially supported by Visual Studio 2017 and above.