»HCP Consul Version Update
You can update your HCP Consul cluster version up to the next higher major version using the HCP Terraform provider. For example: from consul version 1.9.x you can update up to 1.10.x version. There is no anticipated downtime for these updates. HashiCorp will also automatically update your Consul Clusters to fix Common Vulnerabilities and Exposures (CVE). Please check the HCP Portal for the list of available versions of Consul.
»HCP Consul Size Upgrade
HCP Consul offers two production tiers (Standard, Plus). Each of these tiers offer multiple Consul Cluster size (Small, Medium, Large). Using the HCP Consul Terraform Resource you can upgrade your Consul cluster size within a tier using Terraform.
Downgrading size is not supported.