No. DLSS is an fps boost, not a picture quality boost. So generally it should be permanently enabled.
Maxed out is speculative. Cpu sets the fps limit, the gpu lives upto that limit or fails according to graphics details and resolution. But not all in-game settings are graphical, some are cpu bound, so the differences between ultra and high make a fps limit difference.
This is why ppl assume to get fps higher they need to drop settings to low, when in reality that includes setting cpu settings to liw, which raises the fps limit. If you leave those settings low and change the graphical settings to ultra, you start out with maximum available fps. Whether the gpu can put it all on screen is a different story.
Cpu settings include grass...