Yes. FedEx One Rate is a flat rate shipping method that lets you ship in one of the FedEx standard boxes regardless of the weight of the product (under 50 lbs). There are 12 One Rate boxes to choose from. See this FedEx page for more details.
To view FedEx One Rate pricing, select the shipment you are attempting to ship and select package type. You will have your option of One Rate packaging to choose from.
If you’re approved for the FedEx One Rate program, you will see 2 Day shipping rates at One Rate pricing.