Can i change iphone8 to iphoneX

Hello first of all sorry about my english i will try to explain perfect myself. İ live in turkey and i bought İphone8 plus at akasya avm on apple store in istanbul about 1 week ago. I opened and used it just 1 week then i desided to change this phone to iphoneX. İs it possible if i give this phone that store again and i give a little money, and can they change with iphone X? How much will it costs? İ hope i explain myself good:) thank you so much