If you were (even a bad) lawyer you’d know to read the actual law before trying to pontificate on it.
As for the value of privacy policies which you automatically consent to, GDPR Article 6(1):
Processing shall be lawful only if and to the extent that at least one of the following applies:
(a) the data subject has given consent to the processing of his or her personal data for one or more specific purposes;
(b) processing is necessary for the performance of a contract to which the data subject is party or in order to take steps at the request of the data subject prior to entering into a contract;
(c) processing is necessary for compliance with a legal obligation to which the controller is subject;
And now the exact language in Plex’s Privacy Policy that specifically tells you they’re using these provisions to legally process your data and that if you don’t want that then you don’t get the services:
Plex processes and uses Collected Information with your consent, you can withdraw your consent by updating your privacy settings or closing your account. Plex also processes Collected Information when it needs to do so to fulfill a contract with you to provide you services, in its legitimate interest to aid in developing and improving the services, or when required by law. If you do not want to provide certain information to us in order to fulfil our agreement with you to provide the services, we may not be able to provide you the fullest version of our services.
As for your rights as an EU citizen to data Plex collects, Plex Privacy Policy:
If you use our services outside of the United States, we may transfer information from that jurisdiction to the United States, where data protection regulations may not offer the same level of protection as in other parts of the world, such as the European Union. If you use our services in the European Union we will transfer data to the United States subject to standard contractual clauses.
Once Plex transfers your data outside the EU to either their Swiss- or US-based systems it’s game over in terms of GDPR protection for it and Plex is expressly telling you that and you are consenting to it.
As for “You → Plex → 3rd party = covered by plex privacy policy”, again, Plex Privacy Policy:
If you choose to connect your Plex account to a third-party account or service to have us and /or that third party provide a particular feature or service, we will provide that external service with the information needed to have us and / or that third party perform the requested feature or service . . . The shared information may include metadata about the media (such as title, duration, author, cover art, dates associated with the media, and other relevant information) and information about the media itself (such as resolution, bit rate, format, location, etc.).
READ THE DOCUMENTS. You can go on believing all you want about how private your data is under the Plex Privacy Policy and/or as an EU citizen. The fact is that you can, and already have in nearly every circumstance, signed away many of your rights the minute you open a webpage. My “cocky attitude” is based on what the law and Plex’s policies actually say about such things.