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