According to the documentation https://kubernetes.io/docs/tasks/administer-cluster/change-default-storage-class/ if wi want to change the default Storage Class we should patch it.

Template to create new Storage Class

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: encrypted
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp2
  fsType: ext4
  encrypted: true

I have tried to add to the template:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gp2
  annotations:
    storageclass.kubernetes.io/is-default-class: "false"
provisioner: kubernetes.io/aws-ebs

And got an error: gp2 already exist

How to patch/update default Storage Class (make it non-default) with Helm template?