Yes! The Shipping Strategies feature, which is currently in its beta phase, allows you to create groups of services (called "Strategies") you'd like to ShipStation to compare. When you apply a strategy to a shipment (either manually or using an Automation Rule), ShipStation will compare the rates for all services in the strategy and automatically apply the lowest rate to the selected shipment(s).
Review the Automate Selecting the Lowest Rate help article for details on how to create and use Shipping Strategies.
Available to US- and Canada-based ShipStation accounts.
Account must be on the High Volume plan.