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