"C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -h
Usage: C:\Program Files (x86)\Mozilla Firefox\firefox.exe [ options ... ] [URL]
       where options include:

  -h or --help       Print this message.
  -v or --version    Print Firefox version.
  -P <profile>       Start with <profile>.
  --profile <path>   Start with profile at <path>.
  --migration        Start with migration wizard.
  --ProfileManager   Start with ProfileManager.
  --no-remote        Do not accept or send remote commands; implies --new-instance.
  --new-instance     Open new instance, not a new window in running instance.
  --UILocale <locale> Start with <locale> resources as UI Locale.
  --safe-mode        Disables extensions and themes for this session.
  --console          Start Firefox with a debugging console.
  --browser          Open a browser window.
  --new-window <url> Open <url> in a new window.
  --new-tab <url>    Open <url> in a new tab.
  --private-window <url> Open <url> in a new private window.
  --preferences      Open Options dialog.
  --search <term>    Search <term> with your default search engine.
  --jsconsole        Open the Browser Console.
  --jsdebugger       Open the Browser Toolbox.
  --devtools         Open DevTools on initial load.
  --start-debugger-server [port|path] Start the debugger server on a TCP port or Unix domain socket path.  Defaults to TCP port 6000.
  --recording <file> Record drawing for a given URL.
  --recording-output <file> Specify destination file for a drawing recording.
  --setDefaultBrowser Set this app as the default browser.

Bryan@BryanWin10  ~/Documents/GitHub
$ "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -start-debugger-server 6080 -P dev-edition-default
Started debugger server on 6080

Bryan@BryanWin10  ~/Documents/GitHub
$ "C:\Program Files (x86)\Mozilla Firefox\firefox.exe" -start-debugging-server 6080 -P dev-edition-default