I'm not a fan of web novels and I don't have any knowledge about sex conversion comics. Transsexual comics usually referred to the creation of a new type of work by changing the sexual behavior between traditional male and female characters.
Yes, there are many. For example, shonen manga often focuses on action, like 'One Piece' which is about pirates' adventures. Or there are slice - of - life manga such as 'K - ON!' that shows the daily life of high school girls in a music club.
Sex-related manga can be called 'sexy manga' or 'manga with sexual themes'. But be aware that accessing and consuming such content might have legal and ethical considerations depending on the jurisdiction and context.
The manga novel was a comprehensive art form that included many elements such as comics, novels, and illustrations. Usually, the story in a manga novel was created by multiple authors. These authors would each create a storyboard for the story and then draw it together into a complete work. Therefore, manga could be regarded as both a novel and a manga.