Copy Amazon S3 objects from another AWS account

To make sure that a destination account owns an S3 object copied from another account, follow these steps: 1. In the source account, create an AWS Identity and Access Management (IAM) customer managed policy that grants an IAM identity (user or role) proper permissions. The IAM user must have access to retrieve objects from the source bucket …

https://aws.amazon.com/premiumsupport/knowledge-center/copy-s3-objects-account/