Minified version of Brad Gearon's hdr-switch.
Download NVAPI from Nvidia (Version R450 was tested and used) and place it as R450-developer.zip into the root of the project directory.
mkdir bin
cd bin
cmake ..
cmake --build . --target hdrToggle --config Release
The executable can now be found under ./bin/Release/hdrToggle.exe.
.\bin\Release\hdrToggle.exe