There's a new style that's overtaking the world, especially that part of the world that gets its sense of style from Tik Tok. It's called “bookshelf wealth,” but it doesn't require expensive books. You can use whatever you have. In fact, you should use what you have, presuming those are books you have read or to which you are in some way connected.
It is a reaction to artificially styled book collections. Those are collections of books based on color, size, or some such attribute having little to do with the books themselves. They are the type people buy “by the foot” because they meet some physical appearance standard. The “collector” doesn't even need to know what the book is about so long as it has the proper physical aesthetic. A collection of “great books” you would never read just to impress people would also fall into that category. Then there are odd ways of displaying the books, such as the fore-edge out. There's no way you can tell what the book is, or how to find a particular title, but who cares if you like that appearance?
In the above examples, your bookshelves have nothing to do with you, other then, perhaps, revealing your favorite color or some quirky taste. In bookshelf wealth, your bookshelves should reflect who you are. Consequently, the books should be ones you have read, or have other meaning particular to you, such as a gift from a loved one. Nor need your bookshelves have only books on them, though it is appropriate that they be the major item. Photos, collectibles such as figurines, anything that reflects your personality is fair game. Authenticity is the word here. Your bookshelves are you. Therefore, those intellectual prop books people interviewed on TV from home put on their bookshelves behind them are a no-go. If you don't want to read the books, keep them off the shelves. Coffee table books would also be a no.
Extreme order and neatness is not the way either. Your shelves should look like it is your home, not a museum. Not every book should be standing perfectly upright. Some should lean a little, like they had recently been pulled out to read. Putting a few down flat, or even on the floor nearby, is a good look. That's the way you live, isn't it? However, you don't want your books to be messy, just not too neat for a normal human being. Your home should look lived in, but not cluttered. You don't want to look like a neat freak, but not like a slob either.
Of course, there is one weak link in this chain. This is supposed to represent authenticity, but it's a studied, staged authenticity. Isn't “staged authenticity” an oxymoron? Maybe you are a slob. Only slightly messy is not who you authentically are. Maybe you should strive for this, but until you arrive, it's not really authentic. Unless, that is, what you really are is someone who wants more than anything else to conform to the latest styles. In that case displaying faked “authenticity” is who you authentically are and the bookshelf wealth look is perfect for you.