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