Using the Width tool, how do you change just one side of the stroke width?
Select a width point, press and hold the Shift key, and drag on it. Using the Width Tool in Illustrator
You cannot change just one side of the stroke width.
Select a width point and use the Properties panel to adjust the size of each side independently.
Select a width point, press and hold the Option (Mac) or Alt (Windows) key, and drag on it.