Be cautious though, as rclone "sync" is based on file metadata (e.g. last modified), it does not recompute local etags to know which files need to be sync'ed.
For instance, if you "cp -a" a directory and then apply sync, it could do nothing and return success if the copied files were last modified before the ones in S3.
For our use case at work, we wanted to be _sure_ that sync always work as intended, and thus ended up recomputing etags locally and compare to the ones in S3 to know what to sync (got bitten by the issue of last modified before)
RClone: https://rclone.org/ S3 Backend: https://rclone.org/s3/