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.
Complete all chapters
Complete chapter 16
Find Rodric's forge
Complete chapter 15
Complete chapter 14
Complete chapter 13
Complete chapter 12
Find 6 flowers
Save the dying
Craft 100 ammunitions
Complete chapter 11
Complete chapter 10
Complete chapter 9
Complete chapter 8
Complete chapter 7
Complete chapter 6
Complete chapter 5
Complete chapter 4
Complete chapter 3
Complete chapter 2
Complete chapter 1
Find all the flowers
Find 13 curiosities
Find all curiosities
Find all the gifts for the orphans
Fully upgrade the sling
Fully upgrade the equipment
Enter into the 5 alchemist carts
Complete the aiming training
Find a lunch for Hugo
Play hide-and-seek
Save a soldier
Find the tomb
Enter through the main door
Stay with the captain