IntelliJ IDEA provides full coding assistance for developing WordPress including WordPress-aware code completion, search for hook registration functions and functions specified as hook registration parameters, navigation between hook registrations and the hook invocations, callbacks, the possibility to configure the coding style in accordance with the WordPress code style, viewing the official WordPress documentation from the IntelliJ IDEA editor, and so on.
You can run WordPress from IntelliJ IDEA in two modes:
Through a dedicated user interface. To get access to this functionality in a project, you need to download WordPress, register it in IntelliJ IDEA, and activate the WordPress integration within the current project. Follow the process described in Preparing to use WordPress.
Through a set of command line tools. In this case, you need to download WP-CLI and configure it as a IntelliJ IDEA command line tools, see PHP Command Line Tools.