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