No, there are rate limits by IP. If you believe this is possible, try it! Go ahead!
(Now if you have access to 50,000 IP addresses, then yes, that’s a problem, but you also have a lot of money and time. Do you have that amount of money and time?)
That being said I fully support captcha plugins for sites that want double plus good “belt and suspenders and a jumpsuit and a motorcycle helmet and football shoulder pads too” level protection, but the captchas have gotten very very weird lately.