How do I set the il2cpp compiler option?

I want to change il2cpp compiler options directly.

ex) If I want to use rtti, exceptions in gradle I can set the options as follows:

// Sets optional flags for the C++ compiler.
cppFlags "-fexceptions", "-frtti"

However, if you export unity's android gradle project, il2cpp is already built in the exported gradle project.

How do I set the ndk-build option separately when building game code with il2cpp?

thanks.