Google App Engine Standard App has the ability to set the basic scaling configuration with a required setting for a maximum number of instances. Setting this field appropriately will help ensure that an application is able to scale as needed without going beyond a certain number of instances, thus managing the overall cost of the application. For more information on scaling within App Engine Standard App, see the GCP documentation.
References:
https://cloud.google.com/appengine/docs/standard/how-instances-are-managed
The scaling type can be configured via an app's app.yaml file. By default, the app uses automatic scaling, however this can be changed, then applied in a GKE workload.
In Terraform -
References:
https://cloud.google.com/appengine/docs/legacy/standard/python/how-instances-are-managed#scaling_types
https://registry.terraform.io/providers/hashicorp/google/latest/docs/resources/app_engine_standard_app_version#nested_basic_scaling