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