All Aiven services are offered at multiple configurations which are defined as plans. The plan usually determines the number of VMs the service runs in, the high-availability configuration, number of CPU cores and size of RAM and storage volumes. Bigger plans generally also come with features that are not found at all in smaller plans, such as automatically provisioned SSL certificates for all browser-facing services.
A plan can be upgraded while the service is running with minimal disruption. The service is reconfigured to run on larger VMs in the background and once the reconfiguration is complete the DNS names the service uses are pointed to the new hosts. This will cause a minimal disruption while DNS changes are propagated.
If none of our service plans suit your requirements we can also offer custom plans to fit any requirements. Please contact us at firstname.lastname@example.org.