You want use a template to create a new project with network in the Project...

 A template is a predefined structure that can be used to create a new project with network in the Project Builder (CJ20N). You can use different types of templates depending on your requirements and preferences. Some of these templates are:

Standard network: This is a template that contains predefined activities, relationships, milestones, and components for a network. You can use a standard network to create a new network with similar structure and content.

Standard Project definition: This is a template that contains predefined WBS elements, networks, activities, relationships, milestones, and components for a project. You can use a standard project definition to create a new project with similar structure and content.

Project definition: This is an existing project that can be used as a template for creating a new project with network. You can use a project definition to copy the entire structure and content of an existing project or only selected parts of it. Reference: https://help.sap.com/docs/SAP_S4HANA_ON-PREMISE/4dd8cb7b1c484b4b93af84d00f60fdb8/1ad4b65334e6b54ce10000000a174cb4.html?locale=en-US &state=PRODUCTION&version=2020.002