I think reading for me as an adult was the best thing for my writing.
When i was growing up, i read a lot... but all the books i read either had animal protagonists or white (with a few POC characters sprinkled in but always in a "less than" capacity.... like, a book written by a white woman about a slave girl... and a book written by a white woman about a chinese girl who was abandoned).
I hadnt read a book where a POC was a hero or went on fantastic adventures.
Thats not to say they werent there... but until recently, books by minorities or featuring minorities in a prominent capacity were not displayed at book stores and in libraries. You either had to ask for them or look for them. And me as a kid, didnt know to look for them. I just read what was on face out display and what everyone else was reading at the time (fun fact... B&N up until fairly recently only did big displays or face out displays for books that publishers paid them to promote.... and publishers often put the bulk of their promotion into sellable authors. Sellable authors were rarely minorities).
Anyways... my stories growing up were all white protagonists. White pritagonists went on adventures. White protagonists knew magic. White characters lived in tolkien-esque worlds. White protagonists knew vampires and werewolves. Etc.
So my characters were white.
Minority characters had too much trauma and werent "fun" (beloved, ribbons, absolutely true diaries of a part time indian)
Then i started working in libraries and saw all the amazing books by minority authors with minority characters. SFF books and atarted reading more and my writing changed. My characters went from being either white or ambiguous to POC.
I thought i was the only one.... but i attended an author talk where horror author Tananarive Due essentually said the same thing. That until college, the lack of exposure to black books and characters impacted her writing because she never saw black people in the her required reading.