When you upgrade to Cinchy v5 on Kubernetes you are creating a separate instance. You will need to plan the migration of your database, and then follow the deployment installation guide.
To upgrade from v4+ to v5+ on IIS, review the documentation here.
If you choose to upgrade to Cinchy v5 on PostgreSQL, please review the following features that aren't currently available in that deployment.
These may be implemented in future versions of the platform.
No Partitioning
No Geospatial features
No Column Indexing
No Full Text Indexing
No Column Level Encryption
You may also wish to review the list of CQL functions currently unsupported in PGSQL. Please note that this is a living document and that the development team is actively working on function translations between databases. Make sure to check back for the most up to date information.