Right so sat down with my coffee. Just tried a few settings.
4K, no upscaler, direct x 11, everything highest but no RT, motion blur and film grain off I get between 41 and 52 fps.
Same as above, but DLSS on Quality it stays locked at my cap which is 57fps and looking at GPU use it goes down into the 70 percent range so plenty of room there to add more effects or for scenes that require more grunt.
As above but now with Sun Shadows Quality set to RT Soft Shadow I get 45-57fps.
As above but changing DLSS to Balanced now I get 52-57fps. Mostly 57fps now though, just small dips here and there to 55 and I saw one at 52.
As above, but now DLSS set to Performance (basically now upscaling from 1080p to 4K) and now introduced Ultra Quality RT for Global Illumination. Getting 42-57fps.
As above but now adding RT Reflections Ultra Quality I am seeing 40-55fps.
As above but adding RT Ambient Occlusion Ultra Quality and not seeing much difference to fps.
Not bothered with RT flashlight as obviously only at the start of the game so not nighttime yet.
Obviously the above fps numbers just represent day time at the exact start of the game and will vary in other scenes.
Going to now mess about further and then play a bit to see what setting I finally settle down on