Hibernating your Amazon EC2 Instances just got easier. In a single run-instances API call, you can now launch encrypted Amazon EBS-backed EC2 instances from an unencrypted AMI and also enable Hibernation at the same time. You no longer have to create an encrypted copy of your Amazon Machine Image (AMI) as an additional step before launching the instance.

from Recent Announcements https://aws.amazon.com/about-aws/whats-new/2019/05/enable-hibernation-on-ec2-instances-when-launching-with-an-ami-without-an-encrypted-ebs-snapshot/