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