Project templates for C++ and C# for building multi-instanced Universal Windows apps.
This feature is supported in the platform from Windows 10, version 1803 (10.0; Build 17134) onward.
For the C++/WinRT flavor specifically, note that more strict language conformance means that if you target 10.0.17134.0 of the platform you will need to remove the /permissive- flag from the C++ compiler options. Alternatively, you can target 10.0.17663.0 or later. This is described more fully here: https://kennykerr.ca/2018/08/15/compilers-and-conformance/.
The latest version of these templates (1.4) has only been tested on the latest available version of Visual Studio 2017 (15.9.16) and Visual Studio 2019 (16.3.0) Preview 3.0/4.0 at the time of release.
For more information, see here:
Known issues: C++/WinRT CoreApp Redir: bundle packaging fails on VS2017 and VS2019, but single-architecture packages work. This is a general problem and is under investigation.