requestPermission(permissions?: IOSNotificationPermissions): Promise<NotificationSettings>;

Both iOS & Android return an NotificationSettings interface. To check whether overall permission was granted, check the authorizationStatus property in the response:

import notifee, { AuthorizationStatus } from '@notifee/react-native';

const settings = await notifee.requestPermission(...);

if (settings.authorizationStatus === AuthorizationStatus.DENIED) {
  console.log('User denied permissions request');
} else if (settings.authorizationStatus === AuthorizationStatus.AUTHORIZED) {
   console.log('User granted permissions request');
} else if (settings.authorizationStatus === AuthorizationStatus.PROVISIONAL) {
   console.log('User provisionally granted permissions request');
}

For iOS specific settings, use the ios properties to view which specific permissions were authorized.

On Android, authorizationStatus will return only either AuthorizationStatus.DENIED or AuthorizationStatus.AUTHORIZED and all of the properties on the ios interface response return as AUTHORIZED.