If, by ‘original’, you mean the same as your camera’s JPG or preview, then forget it. Your camera applies its own defaults, which only the manufacturer’s software can replicate. This has been discussed ad nauseam on this forum, for example just a few days ago: Simply view original photos without preset history stack..
Though not darktable, but this is well explained here: Editor - RawPedia
And for the details (you’ll have to click the missing thumbnails to display the images – it used to work): Developing a RAW photo file 'by hand' - Part 1