Barely anybody uses pellet extrusion on a 3D printer, and for a good reason. The main development that’s ever happened to that field is when RichRap built the universal pellet extruder, but that was more of a proof of concept and not something actually designed to be used. It’s much more difficult to control and produces much less precise prints for the only advantage of better cost, which could be achieved anyways through a filament extruder. Assuming you were to build yourself a pellet extruder (which is not easy at all and will involve replacing your entire extruder setup), the main issue is that Cura measures its filament in millimeters and you’d have to convert amount of volume of pellets to millimeters of filament. Once you’re done with that, you don’t need to change settings in Cura itself, but you will need to change the extruder steps/mm setting in your printer firmware. But as I said, in general pellet extrusion on 3D printers just isn’t a good idea. If you wanted to take advantage of the cost of pellets, the best way to do it by far is to build a filament extruder or buy a Filastruder to create your own filament from pellets.