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