This node module generates a custom experience builder widget from your command line. You can choose any of the demos in the official ArcGIS Experience Builder page as a template.
Install the package globally:
npm install -g esri-widget-generatorIt will generate the widget in whatever folder you're in -- I'd recommend going to your experience builder folder ArcGISExperienceBuilder\client\your-extensions\widgets
run create-widget
give your widget a name and select the template
that should be it!