Moving data between S3 buckets

It's certainly possible to copy an entire bucket (or a prefix under a bucket) to another S3 location.
If the goal is to have a backup location to an Eon mode database as a DR measure, then Vertica's backup & restore tool is the best fit in our opinion. vbr can still be run on AWS Eon databases and will intelligently copy the data and metadata to a new location, as well as maintain a list of previous backups and the ability to restore a chosen backup. This works for AWS S3, Pure, and Minio Eon databases; for Eon databases on GCP vbr functionality is upcoming in future releases.
If you want to be even lower level then there are many tools that exist to mirror one S3 location to another, even including Amazon's own aws s3 sync utility. Although I would caution that for large databases with massive file counts these may be slow and/or handle transient errors poorly.