When a Scale Out is triggered it affects all resources in your App Service Plan, creating additional VM instances that run your app(s). You will automatically receive additional instances of your application on each new VM based on your Scale Out settings, and these instances will automatically be load balanced by the Azure infrastructure.
It is important to understand that you will now have multiple instances of your application running and load balanced, so it is important to design for this condition. Common pitfalls to avoid are things like sticky sessions, caching issues when requests are served by different nodes, etc. For more information you can view the following links: