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