Azure Web Apps use public endpoints and are usually accessed over the internet without any restrictions. In a case where more isolated access is needed, there is another option: Azure App Service Environment (ASE). Azure ASE offers a fully isolated and dedicated environment for secure applications at high scale. Azure ASE is usually used with workloads that require very high scale, isolated and secure network access, and high memory utilization. As ASE comes as a dedicated environment, this eliminates the problem of noisy neighbors (performance issues that may result from another application sharing the same host) and allow you to fully utilize all resources.
An Azure App Service Plan can be connected to an Azure VNet, but this requires additional work. On other hand, ASE comes automatically connected to a VNet and can be accessed...