Creative writing isn’t the same as opinion writing or other forms of non-fiction. And there is a tendency to choose a side and stay there for the rest of one’s writing life without ever really exploring deeply the extent of one’s capabilities.
Sure, making stuff up in writing is different to conveying a real life experience you’ve had or writing about a subject you possess in-depth knowledge about e.g. academia. But testing yourself by writing on different topics or other interests means you flex your vocabulary ability.
Diversify your reading just as much as your writing. Reading different genres means your style will venture outside your area and be more original, with themes and plots that’ll be more multi-faceted and help your book stand out. Even if it has only one edgy element, it’ll be enough for the reader to recall it.
Originality will begin to seep through, and that is rare in 21st century writing. Where authors will generally jump at popular genres for the sake of notoriety and increasing their profile and likeliness of success with the book (whether to go with popularity or what you like most, it really depends on your goals). Finding your voice is finding the time and space to experiment, what works for you and what doesn’t – don’t be afraid to experiment!