My way of illustrating is to redraw the sketch in vectors, making only the open strokes, not closed, not creating shapes, only intersecting strokes. In Adobe Illustrator there is an interactive painting tool which not only allows you to fill in parts, where there are intersections of strokes, the most spectacular thing about this tool is that it can be expanded, and automatically creates closed forms of each part where the intersections intersect. strokes, I don't know if I explain myself, they would have to use that tool in that software to understand, but I need to create the closed forms automatically in affinity designer.
I attach an image to show what I want to do (this function is made by interactive painting, from the Adobe Illustrator software, it does it automatically), there are some small differences in the images, but it is because I took different strokes already edited