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