```dart
Future<void> uploadPrivateFile() async {
  ...
  // Update the uploadOptions
  final uploadOptions = S3UploadFileOptions(
    // Add the private access level
    accessLevel: StorageAccessLevel.private,
  );

  try {
    final UploadFileResult result = await Amplify.Storage.uploadFile(
        ...
        //Be sure to use the options
        options: uploadOptions,
        ...
    );
    safePrint('Successfully uploaded file: ${result.key}');
  }...
}
```