Assassin's Creed Origins

Early on in the story, you will unlock the ability to craft upgrades to your gear: hidden blade, chest plate, bracers, quiver, etc. that will improve the item’s stats such as damage, health, arrow capacity, etc.

The materials needed to craft such items can be obtained from dismantling gear (best for cedar wood), killing enemies that carry them (wood and iron), hunting animals (by far the most efficient way of getting leathers) or purchasing them.

Simply craft 20 upgrades and the achievement will unlock.