Use the kubectl command to scale a deployment in a Kubernetes cluster.

1. Scale the replicas in a deployment.

   To change the number of instances of the same pod that you're running, you can use the kubectl scale deployment command. For example:

   kubectl scale deployment --replicas=3 hello-world

2. Check the deployment is scaled.

   You can check that the number of pod instances has been scaled appropriately:

   kubectl get pods

   The output looks similar to:

   NAME                           READY   STATUS    RESTARTS   AGE
   hello-world-5db76fbd7d-99s8h   1/1     Running   0          3m46s
   hello-world-5db76fbd7d-g6lrm   1/1     Running   0          15s
   hello-world-5db76fbd7d-h496h   1/1     Running   0          15s