Diễn đàn hỗ trợ Firefox

I can find no recent documentation on command line options for the Firefox Browser. All of the information on this appears to be out of date or just does not work any more (in the latest version June 2021). Is there any documentation on this anywhere that is correct for the current version of the browser? I am specifically trying to run firefox with command line options on Windows 10 but I do not see that that should make any difference. The only option I can get to work is starting firefox with a specific URL; even then I have to change the browser settings to get that to open a new window; because the browser settings override the command line option -new-window