Amplify Console now supports Pull-Request Previews, offering development and QA teams a way to preview changes before merging code to a production or integration branch. A pull-request preview deploys every pull request made to your GitHub repository to a unique preview URL; completely different from the one your main site uses. For apps with backend environments provisioned via the Amplify CLI, every pull request (private Git repositories only) spins up an ephemeral backend that is deleted when the PR is closed.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/10/aws-amplify-console-aannounces-pull-request-previews-for-fullstack-serverless-applications/