n a purchase request case type, you have the following requirement Purchase requests should automatically...

To meet this requirement, you can design a case with a step that routes to the manager. A step is an action that users or systems perform to advance a case toward resolution. You can configure a step to route to a specific user or group of users based on their role, skill, availability, or reporting structure. References: https://community.pega.com/knowledgebase/articles/case-management/88/adding-steps-case-life-cycle