Creating an LLC with books already published

I’ve reached the point in my indie publishing where I’m realizing how much I really need to treat my writing and editing like a business. I’m taking Thomas’s Tax and Business course, but I’m wondering if anyone can offer insight into creating an LLC after already having a couple of books out. Are there extra complexities involved in that? Do I need to change anything in my KDP or IngramSpark accounts or in my books’ copyright statements if I create an LLC at this point? If I take this step, I plan to continue filing taxes as a sole proprietorship for the foreseeable future.