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