If I edit my backup plan and change the storage to Intelligent Tiering (from Standard), will that change happen automagically? Or do I need to change the storage class in the AWS console first? Or do I need to start over with a full backup?
You can edit the backup plan to upload files to Intelligent tier from now on and also create a life cycle policy to move objects to Intelligent tier after, say, 1 day.
Once lifecycle policy moves all objects to that tier you can delete it.
Thanks
Anton