I prefer self-hosting my email using Mail-in-a-Box and have a few AWS servers running on the t2 family. I decided to migrate them to the t3 instances and the process was pretty simple.
After stopping the instance and changing the instance type, I had to enable ENA support on my host. Afterwards, a simple AWS CLI command
aws ec2 modify-instance-attribute --instance-id i-XXXXXX --ena-support was needed before starting the instance.