Configuration files and instructions for installing WordPress securely and running it in a load balanced AWS Elastic Beanstalk environment with an EFS file system for shared assets.
You can include the port in the DB_HOST setting to use a non-default port, but it won't affect setup otherwise. Your change affects the DB_USER setting, though, which is incorrect.
The instructions on the AWS support site tell you to set the RDS_PORT variable, but the config doesn't actually use it. This change uses it.