Amazon Lightsail now supports switching between dual-stack and IPv6-only bundles by removing or adding dynamic public IPv4 addresses on instances.
Previously, you would have to select an IPv6-only bundle and start a new instance from scratch to move from dual-stack to IPv6-only bundles. With this feature, you can switch between dual-stack and IPv6-only plans on a running instance using ‘change networking type’ feature instead of recreating their applications on a new Lightsail instance. This feature makes it easier to test if your application is supported on IPv6-only bundles and only use IPv4 addresses when needed.
You can use this feature on the the Lightsail Console (accessed from AWS Console), AWS Command Line Interface (CLI) and AWS SDKs in all AWS Regions supporting Lightsail. To learn more about this migration functionality, please see documentation here.
Source:: Amazon AWS