I still get a little thrill when I spot a rare free read, but about 'The Lucky Ones'—it depends which title you mean and who published it. If it's a modern release from a mainstream publisher, a legitimately free PDF is unlikely unless the author or publisher has explicitly offered a promo copy. Publishers usually distribute free excerpts or temporary giveaways through Kindle, BookBub, or the author's newsletter rather than full PDFs. That said, sometimes authors put a short story or an excerpt from 'The Lucky Ones' on their website, and those can be free to read.
If the book is older and out of copyright, it could exist on public-domain sites like Project Gutenberg, but most contemporary novels won’t be there. I usually check the publisher’s site, the author’s page, Google Books previews, and library platforms first—those sources let me confirm legitimacy. Personally, I prefer borrowing through my library app or buying a cheap ebook during a sale, because it supports the creators; still, I hunt for legitimate freebies and feel good when I find one that’s genuine.