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