How copy file from RDS to S3 Bucket

To access S3 from RDS, IAM roles must be set up.
Follow the steps in the following document to set up access to S3.
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/oracle-s3-integration.html
https://repost.aws/knowledge-center/rds-oracle-s3-integration

Once you have access to S3, you can upload the dump file by following the instructions in the following document.
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/oracle-s3-integration.html#oracle-s3-integration.using

Incidentally, if RDS is running on a private subnet, a NAT Gateway or VPC endpoint must be configured to communicate to S3.