We know that when creating a virtual machine, you need to determine all its characteristics and what needs to be used. For example, it determines memory, processing, disk space, and various other specifications.
With proxmox, in addition to this initial definition, you can still modify these same characteristics of machines that are already in production. That is, machines already in use can have their spaces expanded if necessary, but also reduced.
This possibility of decrease can be crucial. After all, it is what can ensure that you save resources when realizing that the machine does not need all the memory offered.