To stick with the Google Analytics example, after an opt-out and after the website has been reloaded, Google Analytics would no longer run.
In other cases, the cookie may come from the integration of external content, e.g. a YouTube video or a partner badge, which are integrated with the help of an iframe. This content must be blocked using the Content Blocker. If this does not work automatically, the shortcodes of the Content Blocker must be used.
So if a cookie is already set on the website before you give your consent, you need to find out where the cookie came from. You can find an article that can help you with this here:
Once you have found the location, you need to check if you can simply remove the code and integrate it via a Cookie in Borlabs Cookie, or if you need to use the Script Blocker or Content Blocker.