i want to check whether it is possible to provision multiple APP in single APP service plan in Azure
Yes, that is absolutely possible. In fact, that is a common mistake not to do it. When you create a new service, such as an App Service or Azure Function, you can choose the existing app service plan as the host.
Create the app service plan first, then choose it when creating each subsequent service. It will save you a ton of $$, if you reuse app service plans too.