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