In 2019, I wrote about maintaining my own homebrew formula for X11 emacs. I continue to maintain this bit of code from time to time. Moreover, homebrew no longer support ‘with’ style options (e.g., --with-x11 ) so the installation command has changed:
brew reinstall --build-from-source emacs
You will find homebrew-core in /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core. Once you have my homebrew GitHub fork, run that command to install X11 emacs. There are no additional options with that command. X11 emacs is all you get.