Nope apparently the resolution change is because of something done at low level, raine has absolutely no control on that, it just thinks that the real resolution is the one it displays in video info. And that's the goal of this function anyway to scale the screen and make everything on it to appear bigger.
Normally this kind of thing is handled by a dpi setting, but dpi is mainly for text, then the graphical parts of the interface should scale comparatively, linux seems to do a good job for that, although it's been a long time I have seen a linux or a unix run on some really big screen, but when I switched to linux at university the servers were already using some very big screens !
I am not into the hd stuff because I find usually after 1k the improvement of the picture seems minor in most cases when switching to 2k, 4k, or anything beyond, but the increase in size for the pictures or the videos is absolutely huge, which means more storage, more processing power needed, and all that seems mostly wasted. When you think that we used screens at 576p for pal, and 480p for ntsc until not so long ago and it lasted for tens of years and nobody complained, all this seems quite crazy. But the world is turning crazier and crazier lately anyway !