Signal recently released another grand jury subpoena which, as always, basically had nothing interesting to turn over in response. For the requested phone numbers they could only provide the account creation timestamp. https://signal.org/bigbrother/district-of-columbia/
Signal's recent disclosure of how little it could share in response to a grand jury subpoena is pretty telling. Its defaults are very strong. But if you want to go further, we have a guide on really how to really maximize its privacy settings. https://freedom.press/digisec/blog/locking-down-signal/