The .NET Core framework version 3.1 was released alongside Visual Studio 2019 16.4. The changes include support for C++/CLI components that can be used with .NET Core 3.x, in Visual Studio 2019 16.4. However, not everything works out of the box.
To add support for C++/CLI in Visual Studio 2019 version 16.4, install the Desktop development with C++ workload. This workload adds two templates to Visual Studio:
For core C and C++ support, choose the Desktop development with C++ workload.
The Installation details pane lists the included and optional components installed by each workload. You can select or deselect optional components in this list. For example, to support development using the Visual Studio 2017 or 2015 compiler toolsets, choose the MSVC v141 or MSVC v140 optional components. You can add support for MFC, the experimental Modules language extension, IncrediBuild, and more.