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