To scale out the App Service plan manually, you need to follow these steps:
- Navigate to App Service. Choose the App Service you want to scale up and then click Scale out (App Service plan), as shown in the following screenshot:
- Then, you can increase the number of instances up to the number you want to scale out to.
- Once you are done, click on Save.
You can also do the same by navigating to App Service plans, selecting the App Service plan you want to scale out, and then choosing Scale out (App Service plan).