I’d say both the Witcher 1 and 3 can be enjoyed on a narrative level as standalone titles, though both are significantly enriched by reading the novels prior. The Witcher 1 does have the advantage over 3 in that regard as it spoils next to nothing from the books, as opposed to 3 which pretty much spoils the biggest twist from the end of the books in its opening. So if you decide you like this stuff enough to go back and read the books after 1, youll start more or less fresh.