Azure App Service/Azure Container Registry Identity

I’ve been going through the documentation but I have not been able to confirm this: Is it possible to use SystemAssigned Identity when creating azurerm_app_service_slot or azurerm_app_service resources via terraform?

I know there’s acr_use_managed_identity_credentials and acr_user_managed_identity_client_id but it looks like it only works with UserAssigned Identity. How would I be able to set this to the SystemAssigned Identity Client Id when the resource hasn’t been created yet?