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