Not sure how much help I can get on this, but I'm using a drawing tablet (XP-Pen) with the inkscape calligraphy tool. I created a letter I'm really happy with but am somehow not able to recreate this look. I've been messing with the settings for hours. If anyone who has more experience with inkscape has any ideas I'd really appreciate it. It gets thinner towards the tips and around the curves.
In that style of calligraphy you need to alter the pen pressure depending on the direction of the pen. Down strokes are heavy, and up strokes are light.
Set the Calligraphy Pen preset to No Preset, and use the settings as shown below. If you feel the Mass setting is too heavy, feel free to adjust it a bit lower. The Mass setting will help smooth out your strokes as you draw.
Now it should be possible to draw with varying pressure. You will probably need to practice to get the feel for it. It can be quite tricky to get it right.
For a slightly different look, you can also start with the Dip Pen preset, with the same settings
Another possibility in Inkscape is a totally different approach. You could draw your letter shape with the Bézier tool, and apply a Power Stroke path effect to create thin and thick strokes, using the pink control points on the stroke to vary the width. Obviously this could be useful for those without a pressure sensitive graphics tablet and stylus.
The following example was made entirely with the Power Stroke effect. The plain strokes above, and below altered using the effect.
Here's the Inkscape SVG if you want to examine the construction.