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