That’s a big concern.
Turn Off iPhone Analytics. How to stay as private as possible on Apple’s iPad and iPhone?
make sure to disable all of below settings.
Here is their description:
Share with App Developers:
Improve Siri & Dictation:
Siri and Dictation by allowing Apple to store and review audio of your Siri and Dictation interactions from this device.
Share iCloud Analytics:
Improve Health & Activity:
Help Apple improve health and fitness features by sharing your activity, workout, and health-related data such as physical activity levels, approximate location, heart-related measurements, or ECG classifications.
Improve Health Records:
Help Apple improve the Health Records feature by sharing information such as medications, labs, and conditions.
Improve Wheelchair Mode:
Help Apple improve health and fitness features by sending our wheelchair activity and workout data.
Please let me know if you have any other security setting which is essentials to disable.