Öncelikle "fake-useragent" modülünü kurun.

Random user-agent için örnek kod;
from selenium import webdriver
from fake_useragent import UserAgent

ua = UserAgent()

options = webdriver.ChromeOptions()

options.add_argument(f'user-agent={ua.chrome}')

driver = webdriver.Chrome(options=options)
driver.get('http://whatsmyuseragent.org/')