Xenoblade Chronicles 2 is a bit more open in the sense that there are no invisible walls. Also, battles are more dynamic since those are in real time and on the fly, rather than in a closed space like in DQXI. But even with this aspects, it's shocking to see how much better DQXI looks on portable mode compared to XC2.
I want to believe that XC2 looks so blurry because Monolith didn't have time to polish the game all they wanted... but then again, the expansion suffers the same problem, so...
I don't believe it's that XC2 has more going on necessarily on a scene to scene basis, though it does have a comparatively large amount going on. It's more the image quality solutions. XC2's Temporal Anti-aliasing implementation wasn't done very well and the sharpening filter is used too aggressively. In dock the image quality issues aren't the end of the world and in certain regions they really fade into the background (Leftheria, for example, looks pretty excellent). However, when the resolution starts dropping in handheld mode these issues multiply by a LOT. That's what gives the stress areas in XC2 - the big cities especially - that weird look of being both blurry and crunchy. The camera is also traditionally pulled back a lot and camera movement tends to be faster as a result, which exacerbates the issue compared to DQXI. I will add that XC2 tends to have larger open fields, but there's plenty of compact areas too so it's not all on that. But the roughest region *is* the biggest one with the largest volume of foliage density (Gormott), a region that no region to my knowledge in DQXI matches.
Torna the Golden Country actually did a lot to improve this. The AA solution is much better and the sharpening filter used far more judiciously. That plus further engine optimizations result in a much better overall image in handheld mode for Torna vs base XC2. Dragon Quest XI S from what I have played sits somewhere around the level of Torna, imo. It has some fancy rendering bells and whistles that XC2 Torna doesn't, but then Torna has some tricks of its own like the volumetric cloud simulation and has higher resolution textures in general (though DQXI has a wide variance in texture resolution depending on what the object in question is). It's not quite BotW tier in terms of handheld performance due to it very clearly running in a lower resolution.
Thanks for the input fellas, I actually forgot how big of an area is explorable in XC2 compared to DQXI, I had to watch a video of it to confirm lol, anyways, this is still a great rpg to play for those who doesn't have other platforms to play this on, hopefully this sells well on the Switch.