6 files:

1. %ALLUSERSPROFILE%\Git\Config (Windows only)
2. (system) /etc/gitconfig, with being the git installation path. (on Windows, it is \mingw64\etc\gitconfig)
3. (system) $XDG_CONFIG_HOME/git/config (Linux/Mac only)
4. (global) ~/.gitconfig (Windows: %USERPROFILE%\.gitconfig)
5. (local) .git/config (within a git repo $GIT_DIR)
6. a dedicated file (with git config -f), used for instance to modify the config of submodules: git config -f .gitmodules ...

the command line with git -c: git -c core.autocrlf=false fetch would override any other core.autocrlf to false, just for that fetch command. The order is important: any config set in one source can be overridden by a source listed below it.