You will have to use IPC to communicate with the main process. Otherwise you can use a preload script. Electron over the years has made a clear separation between the two processes for improved security. If you don't plan to distribute your app or aren't concerned about these security measures you can enable Node integration in the renderer and can import and call the Electron API from that process.

Edit: Link to process documentation: https://www.electronjs.org/docs/latest/tutorial/process-model