Is there no way to get argument type-qualifier genericism in C11+ that doesn't involve dispatching to different functions?

Imagine I have a function that is one MILLION lines, and one of those assigns to a "result parameter" (not return value) that I want to be (const char***) or (char***) depending on the argument type used by the user.

I want the QChar from #C23's #N3020 but you know.. for real.