I really dig the OSHA handbook, FM 4-20.100 manuals as well as field safety and health manuals.
On that note, I do believe veering away from the standard story driven narratives can indeed help to broaden your horizon in topics less traversed.
Try some non-contemporary literature - I will individually explain how they affect oneself to apply onto your writing.
1. [Aristotle : Nicomachean ethics]
- This one if you want to learn character development through actions. Make characters more relatable when they have extremes. Eg Corwadice to Rashness
2. [Kant : Groundwork for the metaphysics of morals]
- This one if you want to learn characters being driven by duty, principle and morals rather than emotions
3. [Mill : Utilitarianism]
- Counterpoint to kant one above, help to write villans/characters who act based on results rather than morality. Ends justify the means.
4. [Viktor Frankl : Man's Search for Meaning]
- Understand deep psychological motivations
5. [William Zinsser : On writing well]
- Eliminate all the fluff of your novel writing and be clear
6. [Katherine Boo : Behind the beautiful forevers]
- Actual social realism (written in the setting of a slum), immersion from gripping emotional complexities and challenging circumstances
7. [E.L. James : Fifty Shades of Grey]
- This will be the most important after everything above.
This one. Yes this one. Very important.
I am the expert. No need to thank me.