Amazon DocumentDB (with MongoDB compatibility) now supports an in-place major version upgrade (MVU) from Amazon DocumentDB versions 3.6 and 4.0 to version 5.0 in the AWS GovCloud (US-East and US-West) Regions. Instead of backing up and restoring the database to the new version or relying on database migration tools, you can perform an in-place major version upgrade with a few clicks using the AWS console, the latest AWS Software Development Kit (SDK), or Command Line Interface (CLI). With in-place MVU, no new clusters are created in the process and you can continue using the existing cluster endpoints for your applications.
Source:: Amazon AWS