It's not clear how to use --config-setting - there is only one vague example in the doc and even looking at the source code doesn't throw any light on it.
I did find a few clues in #202, so for example the equivalent command to
$ python setup.py bdist_wheel --build-number 999
is
$ python -m build --wheel -C="--build-option=--build-number" -C="--build-option=999"
As the comments in #202 say, this is unintuitive and is also pretty ugly. Ideally --config-setting could be made more user-friendly, but at least if there were examples like this in the doc it would be more helpful.