Azure portal provides an option to create additional deployment slots for your app to use for staging. This creates a copy of your app which you can publish to for testing and when you’re ready, swap this slot with the production slot. This method of creating a staging slot does not copy over all the files (app’s media or content) to the new slot which is sometimes necessary. To create a new slot with all the files copied over, you can use Azure PowerShell.
Install Azure-PowerShell & Connect to Azure Account
In PowerShell on your PC, install the Azure PowerShell module and connect it to your Azure account.
Clone Existing App to a New Slot
Once you’ve connected to your Azure account, get the details of your app and create a new slot. The parameter that lets you copy all the files to the new slot is
-SourceWebApp in the last command below.