1

Enable iPhone Developer Mode

Deverloper Mode
To allow Flutter to install your app on your device, you must enable Developer Mode:
  1. Open Settings on your iPhone
  2. Go to Privacy & Security
  3. Scroll down and tap Developer Mode
  4. Toggle it on
If you have previously run apps from Xcode on your device, Developer Mode is likely already enabled.
2

Enable Associated Domains Development

Associated Domains Development
To enable your device to bypass the Apple-App-Site-Association (AASA) file cache using ?mode=developer, you must enable Associated Domains Development:
  1. Open Settings on your iPhone
  2. Scroll down to Developer
  3. Tap Associated Domains Development
  4. Toggle it on