For an existing VLAN attachment, you can increase or decrease its capacity as your capacity demands rise or fall. Because capacity changes can affect your service provider's network, you must work with them to change your attachment's capacity. Changes in capacity, in rare cases, can cause traffic disruption. If traffic is disrupted, the disruption lasts less than a minute.
After the service provider has updated your attachment, your service provider works with Google to update the attachment's capacity in your GCP project. At that time, Google updates the charges for the attachment based on the new capacity.
For a list of all the supported service providers, see Service Providers.