How do I enable a configuration in a Kernel?

I am trying to enable KASAN in my Manjaro distribution for a project, but I have no idea how to. The documentation here (https://www.kernel.org/doc/html/v4.14/dev-tools/kasan.html) says just to CONFIG_KASAN = y but I have no idea where to do and what steps should I take before that, I haven't configured the kernel before, I am a beginner. So far I have found out that I can see what configurations are done by looking at /proc/config.gz Here it says that KASAN is not enabled, but I don't know where to go from here. Should I just do an echo CONFIG_KASAN= y, or do I have to rebuild the Kernel and such? Please help me.