Enable auto scaling in existing cluster

I have a production cluster on GKE where I am using istio as service mesh.
Istio was setup using demo profile and there have been lot of configurations done in istio.

Is there a way to enable auto scaling in istio ingress without having to re-install istio? Can I change profile from demo to default without taking down the application.

PS - How many requests can single instance of ingress-gateway handle per second

never use demo profile before, should be possible by adding this on the IstioOperator file right?

    - enabled: true
      name: istio-public-gateway
        app: istio-public-gateway
          maxReplicas: 2
          minReplicas: 1