In order to change the object type you need to copy the original object, set the storage class to one of the following STANDARD_IA, ONEZONE_IA, or REDUCED_REDUNDANCY, delete the original object or overwriting the existing object.

aws s3 cp s3://object-types-solutions-architect/storage-types.txt s3://object-types-solutions-architect/storage-types.txt --storage-class STANDARD_IA

We have changed the storage type by copying the object with a new storage class.