Yes, they can't be signed away. Nuances matter of course, but regarding data privacy rights the general situation is that if you sign some contract with a claus

Yes, they can't be signed away. Nuances matter of course, but regarding data privacy rights the general situation is that if you sign some contract with a clause 'agree to X or we won’t give you service' then that clause is simply invalid as it conflicts with the law and is not binding. If a company would use that data, then they can be fined for using that data without consent since that is not valid (freely given) consent.