No, they don’t. If you’re referring to their ebook selections, they pay for a specific number of licenses to an ebook, then only allow a specific number of patrons to check those ebooks out at any given time. They do this using DRM, to ensure that patrons have their access removed when their checkout period is up. Because refusal to comply would run them afoul of copyright laws and their ebook licensing.
For decades, libraries freely made copies digital media. It’s only been recently that powerful cabals have made it illegal for them to do so.