By default, anyone can access your app using HTTP. You can redirect all HTTP requests to the HTTPS port.
To redirect all HTTP traffic to HTTPS, we recommend the following steps:
Go to the app service custom domains page
In the HTTPS Only toggle, select On.
Full instructions to perform this can be found here at these references: https://docs.microsoft.com/en-us/azure/app-service/configure-ssl-bindings#enforce-https & https://docs.microsoft.com/en-us/azure/app-service/configure-ssl-certificate