For an application to eventually become fully cloud-native, it should follow an iterative process called the cloud maturity model. The first two steps will either require minimal code or simply the configuration changes necessary to connect to Azure PaaS services or to optimize the application for cloud scale. Applications are moved to the cloud, but are mostly using the same code base as they were using when they were deployed on the on-premises systems. The last step, that is, the step to rebuild the application, will require a complete redesign and refactoring of the application. This step will be the most difficult and most intensive part of the application migration process.
The order of this process can be completely random. Organizations can decide to rebuild their applications from scratch to fully modernized applications immediately...