Is it possible to tell, just by the pictures below, if the rear dropouts in the Giant Coldrock can be made longer (to a minimum of 2.5 cm)?
Here are some clipped versions of the best pictures of the bike's rear dropouts I could find:


Giant Coldrock rear dropouts

Giant Coldrock rear dropouts

More pictures of the above frame setup can be found at:
http://vi.raptor.ebaydesc.com/ws/eBayISAPI.dll?ViewItemDescV4&item=184090133650&category=22679&pm=1&ds=0&t=1586797660449&cspheader=1

I have an offer for a complete bike and want to run it with an IGH at times which requires semi-horizontal dropouts to be at least 2.5 cm in length. I know there are other solutions but I want this particular one.

If the above is feasible and safe, any advice on how to do it best in the home shop without special tools will also be greatly appreciated. If possible I'd rather not file away at the dropouts manually but I don't want to damage anything either (apart from manual files, I have access to an angle grinder and battery-operated driver).