Bethesda's official Redfall FAQ has been updated since last week's Developer Direct showcase (which gave us a deep dive into the upcoming FPS), confirming you'll need to be online to play the game. "A persistent online connection is required for single player and co-op," it states, although no reason is offered for Redfall's always-online nature. The FAQ also confirms that you'll need a Bethesda account linked to your Xbox Gamertag in order to play the game.
Redfall will require "persistent online connection," even for solo play (trueachievements.com)
Seems like an odd choice but personally I only game while being connected so idk, not as big as an issue in 2023. This does suck for people/countries that don't have a stable internet connection
Xbox one vision is still alive Kappa