I want to the implementation of the code 'make config' in fedora

It's a bit difficult to understand exactly what you're asking.

The make command is used to compile source code. make will look for a file called "Makefile" in the current directory, and follow the instructions in that file.

make config tells make to look for instructions for building the target "config". make does not know what "config" is, and will consult the Makefile for further instructions.

It's impossible to tell what (if anything) that command will do without knowing exactly what source code you're running make to build.

That may depend on your definition of the word "implementation":

make is a program. You can get the source code of that program and study it and see the real implementation of that command. But I'm pretty sure you won't understand it.

But make is a program that interpretively executes a "program" (a set of instructions) written in a special purpose language. The implementation you probably want to see is those instructions, not the implementation of make itself.

You'll need to read a lot of documentation about make in order to understand the language those instructions are in. Then (as Ser Olmy already explained) those instructions are in a file named Makefile and "config" identifies the final such instruction that make is being told to process. A characteristic of this language is that each instruction effectively identifies other instructions that must be executed before it. So identifying "config" as the last instruction effectively tells make all the instructions it needs to execute.