sdk-for-dart/docs/examples/users/create-target.md

import 'package:dart_appwrite/dart_appwrite.dart';
import 'package:dart_appwrite/enums.dart' as enums;

Client client = Client()
    .setEndpoint('https://<REGION>.cloud.appwrite.io/v1') // Your API Endpoint
    .setProject('<YOUR_PROJECT_ID>') // Your project ID
    .setKey('<YOUR_API_KEY>'); // Your secret API key

Users users = Users(client);

Target result = await users.createTarget(
    userId: '<USER_ID>',
    targetId: '<TARGET_ID>',
    providerType: enums.MessagingProviderType.email,
    identifier: '<IDENTIFIER>',
    providerId: '<PROVIDER_ID>', // (optional)
    name: '<NAME>', // (optional)
);