Schott Music often allows a digital "look inside" on their website or via Google Books. You can legally view the first 2-3 pages for free. This is enough to practice the opening Veiled movement and decide if you want to buy the rest.
For musicians and students:
Let’s address the elephant in the rehearsal room. If you search for "jorg widmann fantasie for clarinet solo pdf free," you will find sketchy links on obscure Russian or Chinese sheet music aggregate sites. Here is why you should not use them. jorg widmann fantasie for clarinet solo pdf free