Yes, our new cropper feature allows you to create borders for resizing your framed prints, rolled posters and rolled canvases in the manual order form. You can also print “full bleed” where there are no borders and the image fills all the available paper.
If you do use the border tool, this will effectively make the image on the paper smaller - e.g. on the image below, the paper size is 8x12" and by setting a 1" border, the image size will be 6x10." The border tool will not make the paper size bigger.
If ordering via API, there isn't an automated way to set borders so these would need to be part of the image you upload.