GPOs – Administrative Templates for Windows 10 v1803 (April 2018 Update) Available

And here are the new admx files for Windows 10 v1803 (April 2018 Update).
Administrative Templates (.admx) for Windows 10 April 2018 Update (1803)

Furthermore, you can find all you can configure with this admx and previous one’s using this guide:
Group Policy Settings Reference for Windows and Windows Server