do you need to buy the deluxe edition of game?

[_Khoja_]

Is deluxe edition needed to play online or gain certain stories?

[Chris P. Nutts]

The Ultimate bundle gives you a huge amount of things like different items, goodies, also some free weapons and a Thoroughbred for single player and also for the online mode. So if you plan to play online with all of the cheaters, account stealers and hackers... well in that case YES, because the horse includes a free insurance and you also save yourself a very long grind for the necessary early game weapons.

If you don't want to play online, there is no real need for more than the base game, all you will miss is an additional treasure hunt and a few, short side quests. (yes, okay and some free weapons you can also buy a bit later) I personally own the Ultimate Version because I'm a fan of the horse including a good starter saddle. (Reverse Dapple Black for SP & Black Chestnut for online. https://reddead.fandom.com/wiki/Thoroughbred )

Game Editions:
https://www.polygon.com/deals/2018/10/18/17991532/red-dead-redemption-2-pre-order-special-ultimate-collectors-edition-bundle-comparison