Here is the full list of all 35 A Plague Tale: Innocence achievements. It takes around 12-15 hours to unlock all of the achievements on Windows.
Find all curiosities
Find all the flowers
Stay with the captain
Find all the gifts for the orphans
Complete all chapters
Complete chapter 16
Find Rodric's forge
Fully upgrade the equipment
Enter into the 5 alchemist carts
Complete chapter 15
Complete chapter 14
Complete chapter 13
Complete chapter 12
Save the dying
Complete chapter 11
Craft 100 ammunitions
Complete chapter 10
Find 13 curiosities
Fully upgrade the sling
Find 6 flowers
Complete chapter 9
Enter through the main door
Complete chapter 8
Find the tomb
Complete chapter 7
Complete chapter 6
Complete chapter 5
Save a soldier
Complete chapter 4
Play hide-and-seek
Complete chapter 3
Complete chapter 2
Find a lunch for Hugo
Complete chapter 1
Complete the aiming training