The phone can either be purchased brand new or preowned.
See link for brand new - https://giffgaff.com/mobile-phones/apple/apple-iphone-6/phone-details
See link for preowned - https://giffgaff.com/mobile-phones/pre-owned/apple/apple-iphone-6/phone-details
It clearly states on each page if it is new or preowned.
I hope that helps.
Untill and unless it is not mentioned as Pre-owned or Re-furbished mean it is New.