How to print the relative url or node id for each referenced node in twig?
You probably need to work more in UI to configure what is in {{ content }} and then render the fields as they are.

If still necessary you can use {{ node }} respectively {{ paragraph }} to access all field values, see How to retrieve value of hidden field in twig?, but you can't access the url directly. You have to build this with the help of the raw database value target id, see How to print the URL path of a referenced node using paragraphs?.

BTW the result is the same as the entity method toUrl() would provide, only that this method is blocked by the twig sandbox policies. As a third (least favourable) option you can change this, too, see https://stackoverflow.com/questions/40091324/allow-new-methods-in-sandbox-policy-in-twig-drupal-8