If they're forcing a fps unlock it'll drop the resolution further, like the other games that do this.
it is always astonishing to see how uniformed people in this supposed gaming forum are... holy shit
they can't do that. and they never did for any other game.
what happened with games that suddenly run at lower settings is that these run in One S mode, they didn't change settings by hand they simply tell the game to run in a different mode.
Dark Souls 3 has only one mode it can run in, this means they can't lower the resolution.
also they almost only force One S settings in games that have a dynamic resolution, because that dynamic resolution will become an issue once you double framerates through the Direct X layer. we have evidence on Series S that dynamic resolutions will not go down even if the framerate goes below the new target.
that is because these dynamic resolutions are set to trigger whenever the game goes below its original fps target. so a formerly 30fps game will only scale the resolution once it is below 30fps, and a 60fps only if it is below 60fps.
patching a game like Titanfall 2 for example will give you major issues because of that. that game has an extremely high resolution ceiling on One X (about 6k, it of course usually runs at only around 1500p) and simply giving this game an fps boost to 120fps means that the game will only start to scale below 6k once it is below 60fps.