Yes, subject to the plans and server capacity available at the time of the request.
Open a support ticket from the client area and name the service you want to change. Include the resource limit that is causing trouble, such as storage, mailboxes, databases, or additional domains.
Support will confirm the available plan, price, billing effect, and any work required before making the change. Do not cancel the existing service to request an upgrade because cancellation can schedule its data for removal.