While searching through RDR2 Files i found this Starfield Texture. I tried it, it looked good so i am sharing it. Its not 4k so no fps loss.
Install:
mods/update/update.rpf/x64/textures/skydome.ytd
mods/x64a/textures/skydome.ytd
Right Click on skydome.ytd, choose edit, drop the starfield.dds into the OpenIV Texture viewer, click save and you’re done.
Watch the Picture in Fullscreen
Credits:
MaxLuk