iPhones encrypt everything locally, as well as in iCloud, iMessage, and FaceTime. No apps can access any data outside of data entered into the app itself without explicit user consent. They’ve repeatedly fought the FBI on creating backdoor access, and have yet to lose. They only collect anonymous user data for in-house engineering if the user chooses to opt-in. If you ask for your GDPR abstract of data from Apple, it will only include your name, billing address, and phone number. Apple is big on privacy.