Is it possible after setting selenium webdriver to a headless mode set it back to a normal mode?
from selenium import webdriver
from selenium.webdriver.firefox.options import Options
options = Options()
options.headless = True
driver = webdriver.Firefox(options=options)
driver.get(http://stackoverflow.com)
# set driver back to normal mode
No, it won't be possible to make Chrome operate initially in headless mode and then switch back to normal mode within the same session.
When you configure an instance of a ChromeDriver with ChromeOptions() to span a new Chrome Browsing Context the configuration gets baked within the chromedriver executable which will persist for the lifetime of the WebDriver and being uneditable. So you can't modify/add any existing/new configuration through ChromeOptions() class to the WebDriver instance which is currently in execution.
Even if you are able to extract the ChromeDriver and ChromeSession attributes e.g. Session ID, Cookies, UserAgent and other session attributes from the already initiated ChromeDriver and Chrome Browsing Session still you won't be able to change the set of attributes of the ChromeDriver.
A cleaner way would be to call driver.quit() within tearDown(){} method to close and destroy the current ChromeDriver and Chrome Browser instances gracefully and then span a new set of ChromeDriver and Chrome Browser instance with the new set of configurations.
You can find a couple of relevant discussions in: