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