for reference: Can you get all items in Red Dead Redemption 2?
As far as I understand, the “bank robbery” mission is the only new quest. The “gang hideout” is only an added location I assume (maybe with reused assets even).
After taking a cursory glance at Youtube videos, the mission doesn’t last longer than ten minutes. The gameplay boosts are entirely trivial to me and to my knowledge Rockstar hasn’t adjusted the progression after reviews came out (to introduce potential grind).
The ultimate edition has only online bonuses (boosts, cosmetics, a horse).