The dwarf sprites are the gold standard for the pixel dpi for the sprites in the game. The hexagon tiles are at a scale of 50x40 pixels. You can use this as the template for how big to draw your sprites. A standard sprite config file has the draw scale set to 0.55. This arbitrary-looking number is because the engine doesn't render in accordance with pixels, but instead the hexagon shape's coordinates as integers, and the engine scales efficiently to increments of 0.5.
If you're out though, that's ok! You can set the draw scale to whatever you want!