sdk-for-dart/docs/examples/backups/create-archive.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

Backups backups = Backups(client);

BackupArchive result = await backups.createArchive(
    services: [enums.BackupServices.databases],
    resourceId: '<RESOURCE_ID>', // (optional)
);