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