Yes, it would.
But XIV uses proprietary, spaghet engine.
At baseline, if PS5 gameplay is optimized (or is it still PS4 ?), really the difficulty of implementing DLSS may not be worth it.
Baseline today would be PS5/PS4 and 1080p resolution and DLSS would at least require imo nvidia 20 series or AMD 6000 series.
At baseline, many XIV PC players might can say that they do not have at least that. Due to the market, I have been stuck with a 480RX for quite sometime but I can still maintain 75fps @ 1080p.

It's been quite some time since I've heard back about DLSS, but this of course because I am an avid AMD fan.
Anyone else more knowledgeable feel free to correct me.