When drawing lines and figures with Clip Studio Paint, using a [Vector Layer] is quite helpful. When you use drawing tools such as pens, brushes, and graphics tools on a vector layer, lines are created in vector format.
※Vector layers cannot be used on DEBUT.

<What is a vector layer? >
While it cannot paint color or process filters like you can on a standard layer (raster layer), a vector layer is an excellent layer to create linework on.
Lines drawn on a vector layer can have their line type, thickness, and shape freely adjusted afterward. Furthermore, line quality does not diminish when scaled up or down.

How to download                  

① Create a vector layer from the [Layer] menu ->[New Layer] -> [Vector Layer], or select [New vector layer] from the [Layer] palette.

② Use a drawing tool such as the pen or brush tool or a graphics tool such as the figure tool. If you draw using long strokes, it will be easier to adjust afterward. Adjust any line distortion with the [Object] tool.

③ Thickness and line type can be changed from the [Tool Property] palette while the [Object] tool is selected.

On vector layers, you can also use the [Eraser] tool -> [Vector] to erase up to where the lines intersect.

For details on vector layers, please refer to this article.

How to use a Bezier curve