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