C++/WinRT is Microsoft's recommended replacement for the C++/CX language projection, and the Windows Runtime C++ Template Library (WRL).
The Windows SDK includes C++/WinRT; it was introduced in version 10.0.17134.0 (Windows 10, version 1803).
If you open the developer command prompt for VS 2017 and type:
it will display the compiler path location and version
C:\Program Files (x86)\Windows Kits\10\bin\10.0.17763.0\x86\cppwinrt.exe