I bought the 12 mini from that store in the 8/8 sale. Arrived 2 days later, all sealed up. Turned on and it immediately updated to the latest iOS, the I put next to my iPad and they synced and set up the phone. I got the 3 months free offers on Apple Arcade and Apple TV+. It also shows that AppleCare coverage is available via Settings.
It certainly isn't fake, nor second hand and I am perfectly happy with it.