Grid upgrade possible in ExaCC

Hi

I have understood, that while creating vm cluster from ExaCC cloud, you must specify grid version. And I have heard that rule of thumb is to always select latest release version, since it cannot be changed later on or it will be very difficult.

My question is, if one has created a vm cluster with grid version 18c, then can it be upgraded to 19c..? (X8 and X8M)

Or this is only possible by creating entirely new vm cluster..?

For databases release, db can be upgraded only to max release version as the present grid is. So if grid cannot be upgraded to 19c, then same applies probably to databases.