Private registry: port not building correctly

[zvilius]

I am experimenting with creating a private vcpkg registry. My sample_registry has one port: libsample.
libsample is a simple static library with one function: greet().

After a lot of effort, I got it all pieced together, and I can successfully build and run my sample project which gets libsample from sample_registry and calls greet(). *whew* [Editorial comment: that was really hard. There isn't a single good source of documentation for that process.]

However I looked at the libsample.lib binary and it's 340 kB in both the build/x64-release and build/x64-debug trees in my sample project. When I build libsample "by hand" with:

> cmake --preset=vcpkg -DCMAKE_BUILD_TYPE=Debug
> cmake --build ./build

.. I get 221 kB for Debug and 79kB for Release.

How can I debug the build that is triggered by vcpkg/cmake when libsample is downloaded from the private registry? As a start, how can I see the cl.exe command line that is generated so I can understand why the vcpkg build doesn't match the "by hand" build?

(My development environment is Windows, Powershell, MSVC with CMake.)