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