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