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