Harness facilitates seamless cross-account access to S3 buckets for artifact management, streamlining DevOps practices by allowing production accounts to securely retrieve artifacts from a central DevTools account, which enhances efficiency and security in multi-account AWS environments. The process involves defining a good artifact source and implementing a well-structured S3 bucket policy based on the principle of least privilege to ensure secure cross-account access. This setup requires connecting Harness to the AWS account using necessary IAM roles and policies, while maintaining a continuous effort to adapt to changing security needs. Although the Harness and AWS CLI do not list cross-account buckets, the API can still retrieve objects, enabling effective use of S3 as an artifact source.