Can a constantly blocked nose cause dark purple color undr eyes.and can it cause dark skin of face.like blue. body skin is so fair?

'Shiners': that's the name of the dark discoloration under eyes for people who have nasal congestion, due to back pressure and engorgement of veins under the thin skin below lower eyelids, treatment of congestion would help relief this. Blue hue of the whole face is unlikely related. You want to see an ENT specialist for assessment, start with your primary doctor, meanwhile, frequent saline washes would help