Here is the full list of all 51 Red Dead Redemption 2 achievements. It takes around 200 hours to unlock all of the achievements on Windows.
Survive 18 bear attacks and kill the bear each time in Story Mode.
Attain 100% completion.
Find a permanent home for the squirrel statue.
Study every animal across all states in Story Mode.
Skin every species of animal in Story Mode.
Find the graves of each of your fallen companions.
Complete one of the Collectable strands.
Survive 3 days holding a bounty of $250 in all states.
Earn 70 Gold Medals in Story missions.
Complete the Epilogue.
Complete 'A New Jerusalem'.
Complete 'Red Dead Redemption'.
Complete all optional Honor story missions.
Complete 'Goodbye, Dear Friend'.
Craft 30 unique items in Story Mode.
Catch a fish weighing at least 16 lbs (7.3 kg).
Recover the stash from 4 homesteads.
Reach maximum or minimum Honor level.
Complete Chapter 5.
Complete Chapter 4.
Complete 10 Stranger mission strands.
Discover the fate of Marko Dragic.
Complete a Companion Activity in each camp.
Spend $5000 across all shops.
Complete Chapter 3.
Complete Chapter 2.
Upgrade each available component for a single sidearm or longarm weapon.
Rob or loot $250.
Deliver 5 camp companion item requests.
Play all mini games.
Donate $250 to the gang tithing box.
Red Dead Online: Reach Rank 50.
Red Dead Online: Complete a Free Roam mission as part of a Posse with at least 2 members.
Red Dead Online: Purchase 5 camp improvements.
Red Dead Online: Craft 20 items (excluding ammo).
Red Dead Online: Craft 25 pieces of ammunition.
Red Dead Online: Form a Persistent Posse.
Red Dead Online: Concurrently own 5 horses.
Red Dead Online: Successfully counter a rival Posse's Free Roam mission.
Red Dead Online: Play 5 Free Roam Events.
Reach max bonding level with a horse.
Red Dead Online: Pick 25 Herbs.
Red Dead Online: Achieve 5 gold belt buckles from awards.
Red Dead Online: Achieve MVP 3 times (in a round with at least 4 players).
Red Dead Online: Accept 10 Free Roam missions from characters around the world.
Red Dead Online: Take part in a Series.
Red Dead Online: Sell 20 items to the Butcher.
Red Dead Online: Reach Rank 10.
Red Dead Online: Complete the Intro.
Complete Chapter 1.
Complete 'Enter, Pursued by a Memory'.