If the lines in the CDR want to look good, they can't be directly regarded as lines. To look good, the lines need some changes, such as those in Japanese comics. Generally, when turning, it will be handled rudely and realistically. This can't be done by adding bold lines directly to CDR, because if you want to bold, the whole thing will be thick. You should set the line of the graph to none, then copy the graph, with the lower layer filled with black and the upper layer with the original color, and then use the shape tool to adjust the shape edge of the lower layer, or narrow the shape edge of the upper layer, that is, the black shape edge of the lower layer is exposed, thus making a "line" that can be adjusted at will.