Most likely you will be able to compile your c file from the Developer Command Prompt for VS using the command: cl <source code file path>
This is because the Developer Command Prompt for VS loads all the environment variables needed to find the standard c libraries, that are distributed in various Visual Studio and SDK paths in Windows.
The three key environment variables for C library locations are: INCLUDE, LIB AND LIBPATH.
You can solve this problem permanently by creating these three variables in your Windows Environment Variables (system variables) and populating them with the values used by the Developer Command Prompt for VS.
To see the values to use, run the set command in the Developer Command Prompt for VS. If you also run the set command in a normal windows command prompt you can Diff the two outputs and see what you are missing outside the Developer Command Prompt for VS environment.
There's probably a better way to configure the build tools in Visual Studio Code to find the C standard libraries for building and debugging, but I haven't worked out where to do that.