App service plan : per_site_scaling


I want to create an app_service_plan which would be able to scale up, but il will contain an app service which will be unable to scale.
To do that, I want to use the per_site_scaling but i am unable to find an example or documentation from terraform. Microsoft says that to prevent an app service from scaling out, in such a case, we have to set numberOfWorkers to 1 inside the app service, but i can’t find how to do it using terraform.
Could you help me ?