How to tell Xcode13 to use GCC for building C++ projects?

I have GCC installed and require the ability to use some libraries that are only supported in C++20 for now. In the project build settings in Xcode, how do I use the GCC compiler instead of the libc++ compiler used by default?

This question appears to have been asked earlier last year however has not been answered.

GCC is no longer supported by Xcode.

How to tell Xcode13 to use GCC for building C++ projects?
 
 
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