Absolutely, they can and many reputable ones do. It's a standard practice used by major retailers and official publisher platforms as a legitimate marketing tool. Think about sites like Amazon's 'Look Inside' feature or Google Books' previews—those aren't piracy. They're negotiated with publishers and authors, giving readers a legal sample to decide on a purchase. It's like browsing in a physical bookstore; you're allowed to read the first few pages.
From what I understand, the legal framework usually involves setting limits, like showing only the first chapter or 10% of the book. This respects copyright by not giving away the entire work for free. It serves the core discovery intent: letting you check the writing style, meet the main character, and see if the plot hooks you before you commit your money or time.
Some platforms tie these previews into their subscription models too. You might get the full first chapter free, then need a membership to continue. It's a win-win—readers get a risk-free try, and creators drive conversions. I always look for this feature; it saves me from buying books I end up disliking. The key is using the official storefronts linked to the publishers.
I've seen some smaller, independent author sites even offer more generous samples, like the first three chapters, directly as a way to build an audience. As long as the copyright holder authorizes it, it's completely above board. It's the unauthorized full-book uploads on random forums that are the problem.