There is also a list of what most of these flags do beneath the flag itself:
Also here (these likely need to be updated): https://support.brave.app/hc/en-us/articles/360044860011-How-Do-I-Use-Command-Line-Flags-in-Brave
And then all the ones used by Chromium:
If there is a particular flag you’re curious about or not quite sure you understand, you can just ask what the flag does and we’ll do our best to assist.