You don't generate them. These are hand-drawn illustrations.I found this:
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I saw many pictures like this on WikiHow and I want to know if these pictures are hand-drawn or generated using software?
Looks manually drawn to me. You could probably trace these from real images, and add color/highlight/shade to the objects. If you are looking for an opensource vector editing sw, try inkscape. There are lots of tutorials available for this sw as well. I recommend “logos by nick” youtube channel for example (not affiliated).I found this:
View attachment 275264View attachment 275265
I saw many pictures like this on WikiHow and I want to know if these pictures are hand-drawn or generated using software?