Create a new window containing the settings page.

settingsPage.js

function createSettings() {
  settingsPage = new BrowserWindow({
    parent: win,
    width: 500,
    height: 310,
    webPreferences: {
      nodeIntegration: true
    }
  })

  settingsPage.loadFile('./pages/settings.html');

  settingsPage.on('closed', () => {
    settingsPage = null;
  })
}