I believe the main argument for -X options is the fact that cmd on Windows doesn't offer a nice way of setting environment variables as part of the command invocation (hence "-X utf8", for example).

As far as setting values for X options goes, `sys._xoptions` in CPython is a str:Union[bool,str] dict, with the command args split on "=":

$ python3 -X arg=value -c "import sys; print(sys._xoptions)"                                                                                                                  
{'arg': 'value'}

If no value is given for the arg, then it's just set to the boolean True.

The _xoptions entry shouldn't be the public API though - it's just a way of shuttling settings from the command line through to CPython-specific initialisation code.