This is a really high compliment thank you anon :') It's not an IQ thing, I had my IQ tested along with everything else when I was 13 and was in testing for autism but IQ is notoriously unreliable. IQ itself doesn't really mean anything.
Reading is a good idea! Reading a lot will help you structure your sentences more easily because it will improve your vocabulary. I've always been naturally very drawn to writing and analysis, but I've also been an avid reader my entire life. I think reading is a very good way to beef up your vocabulary and study how other people structure sentences (this helps with writing in general too, you can't improve your writing if you don't read). I also write essays and read research papers for fun but if you have to force yourself to do that, I wouldn't overwork yourself (I do it because I think it's fun and good practice). I can't say I recommend any specific books, because I've never read a book that's touted to improve your articulation. Having a large vocabulary can help, because using hyperspecific words can express more in certain scenarios, but you do not need to use big words to sound smart. You also shouldn't utilize words that you aren't confident you understand, because misusing words is a major detriment to people understanding you. Words don't always mean what their roots might imply they mean, though that's usually a good reference point. (As an example, I see people use the word "ambivalent" as a synonym to "impartial" when it doesn't mean that, and "enormity" doesn't mean "sheer size", it's exclusively a word to signal how immoral something is on a scale. For example, the quote "the enormity of my desire disgusts me" from Richard Siken does not refer to unmanageably sized desire, but instead, desire perceived as extremely evil or wicked. People think "enormity" is the state of "being enormous", an adjective that does refer to solely size, rather than a word of its own, because of how the word is structured. "Ravish" is often used as a synonym for the act of having passionate sex, when it super, really, extrremely doesn't mean that. Of course, people make mistakes.)
Honestly, I think a really significant part of it is just that I grew up autistic and I had to express myself a lot more concisely than other kids/teenagers, and it's a skill I gradually learned over time. It just translated to things like writing and posting about characters I really like on the internet.
TLDR: Read a lot and make sure you understand the words you're using.