If you begin to outgrow the resources of your WP Server, talk to WP NET Support and we'll advise on the best course of action.
While it is sometimes worthwile to run an "in-place" upgrade (extra CPU and memory resources are added to the server without ANY other changes) it is often best to provision a fresh new server and migrate the data across. This ensures that your server is running the latest and most secure versions of software packages, and that the latest best practice has been implemented in the software configuration.
Please note that is never possible to downgrade and "shrink" a single-tenant WP Server. If you want to move your site to a smaller server, we usually recommend that we provision a fresh server and copy your data over. Open a support ticket for assistance.
If you need to upgrade or downgrade a WP Server (or Managed Server (legacy)), please open a support ticket and we'll be happy to help.