paragraphs
There's no software I know of that can help with paragraphs. There isn't even a hard and fast rule for what a paragraph should be in fiction. Nonfiction paragraphs do usually follow a set rule, but paragraphs in fiction are there almost as much because they read well, and do the job the writer wants them to do, rather than because of grammar or style rules.
A single scene may have one paragraph, or two hundred paragraphs, and it's unlikely any two writers would use the same number of paragraphs, even when writing the same scene.
Which does not mean you can break paragraphs wherever and however you want, unless there's a good reason for doing so, but it does mean that I seriously doubt you'll find any software that tells you how to write paragraphs in fiction.
I do think it pays to know exactly what a nonfiction paragraph should be, and to follow tis loosely, but in fiction, a paragraph is largely about feel, style, effect, and pace, while still making sense as a single unit of thought, action, or description.
I wouldn't worry too much about it. Read novels by good stylists, and trust your instincts. You may not need as much help as you think.