Here is the full list of all 35 A Plague Tale: Requiem achievements. It takes around 20-25 hours to unlock all of the achievements on Windows.
Fully improve the Opportunism skills
Shoot all the pine cones
Open all the secret chests
Find all feathers
Recall all souvenirs
Successfully complete all throws in the Crowns game
Fully improve the Prudence skills
Find all flowers
Complete all chapters
Complete chapter 16
Fully upgrade the gear
Fully upgrade the alchemy
Complete chapter 15
Complete chapter 14
Fully improve the Aggressive skills
Complete chapter 13
Fully upgrade the sling
Complete chapter 12
Complete chapter 11
Complete chapter 10
Complete chapter 9
Interact with all the old protector’s items in the sanctuary
Fully upgrade the crossbow
Complete chapter 8
Complete chapter 7
Extinguish 40 fires
Complete chapter 6
Fully upgrade the instruments
Complete chapter 5
Complete chapter 4
Craft 100 ammunitions
Don't kill the guard on the docks
Complete chapter 3
Complete chapter 2
Complete chapter 1