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