The KnowledgeC data base is extremely important to forensic investigations, but it does require additional access to obtain a full file system dump. This file is located in /private/var/mobile/Library/CoreDuet/Knowledge directory. You will find that this file is a merge of system artifacts and user artifacts that may be useful to your investigation.

Sarah Edwards wrote a helpful blog, which can be read here: https://www.mac4n6.com/blog/2018/8/5/knowledge-is-power-using-the-knowledgecdb-database-on-macos-and-ios-to-determine-precise-user-and-application-usage. Another helpful blog is explained by the view of Ian Whiffin and can be found here: https://doubleblak.com/blogPosts.php?id=2