There is some weirdness. I've heard 4K resolution might appear in settings once you're in-game rather than menu. You might have to cycle through borderless/fullscreen/windowed for it to show up.How do you change resolution above 1080p? Mine is stuck at 1920x1080 even on a 4K screen. I guess you can uncap framerate by turning off vsync? Because right now mine seems to be locked at 60.
My game seems to be capped at 60hz in Fullscreen mode no matter what Vsync setting is used. When I switch to Borderless (Vsync off), there seems to be a 120fps cap. When I use Borderless with Vsync on, my full 180hz refresh is used.
So for me the optimal settings are Borderless with in-game Vsync turned on. I'm actually on 1080p resolution with 200% scaling rather than 3840x2160 since my monitor is 1080p. 140-160 fps, so I capped at 140 in RTSS.
I generally dislike Borderless modes and in-game Vsync, but eh, it's a turn-based JRPG. I'm not going to notice any input lag -- or care, even if I did.