Any digital images that you purchase will be sized at 10×8″ at 300ppi in JPEG format as standard. This is perfect for printing up to this size or slightly larger (you have more flexibility on size when it comes to canvases as they are printed at a lower resolution).
If you know you want to print significantly larger than this, you can upgrade your digital images to be larger file sizes and they will be sent to you on USB drive – just check your gallery pricing for the options here.
One little note though – always back up your USBs – they’re aren’t the most reliable technology for long term storage.