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
Fully upgrade the equipment
Find 6 flowers
Complete chapter 14
Complete chapter 13
Complete chapter 12
Save the dying
Complete chapter 11
Fully upgrade the sling
Complete chapter 10
Find 13 curiosities
Craft 100 ammunitions
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
Complete the aiming training
Find all the flowers
Find all curiosities
Find all the gifts for the orphans
Enter into the 5 alchemist carts
Find a lunch for Hugo
Play hide-and-seek
Save a soldier
Find the tomb
Enter through the main door
Stay with the captain