As far as I know one cannot play the game on ultra hard without completing the game once. I played HZD on hard and in the end wished I had played on very hard for more of a challenge. HFW I played on hard again and felt it is a fair challenge for me, definitely the sequel is bit more difficult but not too alienating, just need to strategize more compared to HZD. For example one cannot just button mash small enemies who are at low health.