some of the older carpenters and cabinetmakers will have the necessary traditional planes for cutting these profiles or you could have one made out of plaster, cement.or builders bog moulded out of a cast made from the remnants of the original board or try a high tech solution with a copy made with a 3D printer or two separate lengths of moulded timber attached together to approximately match the original but you'll need to research plaster works, restoration companies, specialist carpenters and tech colleges for a computer, woodworking or art student keen to try an interesting project but you may find that it's quicker and easier to replace the whole section with an unmatched section of plain skirting board or try stealing a section from somewhere else in the house where the skirting board is hidden behind a bed or lounge and replace the hidden area with the plain board...best of luck with your repairs

Hi

That doesn't look like a skirting board to me. It looks more like an architrave from the short profile. Not sure which state you are in but do a search for architrave suppliers in your area and online.

Cheers