Extending the current XYRS format to also specify width and length would make building a standard XYRS file easier. I don’t want to make assumptions, but these measurements seem simple to export since the parts are usually rendered during PCB Layout.
Macrofab’s format looks like this.
#Designator X-Loc Y-Loc Rotation Side Type X-Size Y-Size Value Footprint Populate MPN
J4 423.2283465 256.8897638 0 2 1 248.032 598.031 3220-14-0300-00 CONN_HDR14_SMT 1 3220-14-0300-00