Both, and my question was aswell where can I find the options for that?

pytest has its own repo: https://github.com/pytest-dev/pytest (lots of command-line options).
It also has several plugins, such as pytest-xdist (which provides the multithreading options):
https://github.com/pytest-dev/pytest-xdist

For a list of Chromium command-line options, see: https://peter.sh/experiments/chromium-command-line-switches/
SeleniumBase already uses many of them, and has its own args for enabling the ones that aren't enabled by default.
Use SeleniumBase's chromium_arg to pass a list of comma-separated Chromium args if there's no direct arg for it.

The SeleniumBase pytest args are listed here: SeleniumBase/help_docs/customizing_test_runs.md

I meant for the raw driver

More info on using multiple proxies: #1832 (comment)

Got it, thanks!

Quick question, for raw driver how do I change window height/width? I assume 'd_width=None, # Set device width
d_height=None, # Set device height
d_p_r=None, # Set device pixel ratio' are different and relating to different things? if so, what exactly?

Those are for mobile device metrics. (Something different, only for mobile mode.)

You want this: driver.set_window_size(width, height)

(It is set after the browser is launched.)

Ah ok I see, where can I find the list of the '.sets' available for raw driver such as that one?

If it's already included with raw selenium (eg. driver.set_window_size(width, height)), then it won't be listed in the SeleniumBase Docs. (It's probably already somewhere in the Selenium Docs.)

But there is a section for driver methods that were added in SeleniumBase: #2200 (comment)

I'm not sure what you mean by this. Chrome is what it is. There are options available so that you can customize Chrome. SeleniumBase provides command-line options and method args for making those customizations, as listed in the comments above.

I meant modify the Chromium source code itself then rebuild to be used with selenium base or is this just making it detectable and maybe a monkeypatch is better or?

"modify the Chromium source code"

I don't know anything about that. UC Mode modifies chromedriver (not Chrome / Chromium).
Most Chromium browsers are just modified versions of Chrome anyway (eg. Brave or Opera).

That's what undetected/patcher.py does.

Noted, just a quick question, how do you know here where to and what to patch if you have the time to do a quick walkthrough?

def patch_exe(self):
 """Patches the ChromeDriver binary"""
 def gen_js_whitespaces(match):
 return b"\n" * len(match.group())
 def gen_call_function_js_cache_name(match):
 rep_len = len(match.group()) - 3
 ran_len = random.randint(6, rep_len)
 bb = b"'" + bytes(str().join(random.choices(
 population=string.ascii_letters, k=ran_len
 )), 'ascii') + b"';" + (b"\n" * (rep_len - ran_len))
 return bb
 with io.open(self.executable_path, "r+b") as fh:
 file_bin = fh.read()
 file_bin = re.sub(
 b"window\\.cdc_[a-zA-Z0-9]{22}_"
 b"(Array|Promise|Symbol|Object|Proxy|JSON)"
 b" = window\\.(Array|Promise|Symbol|Object|Proxy|JSON);",
 gen_js_whitespaces,
 file_bin,
 )
 file_bin = re.sub(
 b"window\\.cdc_[a-zA-Z0-9]{22}_"
 b"(Array|Promise|Symbol|Object|Proxy|JSON) \\|\\|",
 gen_js_whitespaces,
 file_bin,
 )
 file_bin = re.sub(
 b"'\\$cdc_[a-zA-Z0-9]{22}_';",
 gen_call_function_js_cache_name,
 file_bin,
 )
 fh.seek(0)
 fh.write(file_bin)
 return True

You should ask the maintainer of undetected-chromedriver.
It came from undetected_chromedriver/patcher.py