You want to dev a React Native app that uses a self-signed certificate. iOS thinks that’s a bad idea.
How can you install trusted certificate on iOS emulator?
Download root CA.
Drag/drop onto emulator. It should open Safari (if nothing happens, cancel and you’ll see the next step).
Allow the download, adds a profile to settings.
Navigate to settings > profile > YOUR ROOT CA, click install, confirm and install, and again
Navigate to settings > about > Certificate Trust Settings, enable full trust for YOUR ROOT CA.