Horizon Forbidden West's PS5 upgrade path will be exclusive to its more expensive editions.
Sony and Guerrilla Games outlined the game's many variations in a recent blog post, and an accompanying FAQ confirms that you can't upgrade from the PS4 version of the game to the PS5 version unless you purchase its digital deluxe, collector's, or Regalla edition. "Dual entitlement does not apply to the standard and special editions," Sony says.
The $69.99 standard edition and the special edition seem to be mostly the same, with the latter only available in limited quantities since it bundles in a steelbook case, art book, digital soundtrack, and bonus outfit. The digital deluxe edition, which is $79.99, comes with more noticeable additions like in-game bonuses and cosmetics.
The main takeaway is that you won't be able to upgrade from PS4 to PS5 unless you spend at least $79.99 on your initial purchase – and initial is a key word here. The aforementioned FAQ also states that "there are no plans for an update offer from standard to digital deluxe edition at this time," so you apparently won't be able to buy the standard edition for now and decide to upgrade later.
Together, this frames a much more restrictive upgrade path than previous cross-gen titles, and with Horizon Forbidden West positioned as one of the PS5's tentpole first-party games, it's possible that this will become standard practice going forward. We've reached out to Sony for more information and will update our reporting if we hear back.
Last week, the Horizon Forbidden West release date was delayed to February 2022.