This repo contains a wordpress example theme. The theme uses the official @wordpress/scripts package to power the JS(X) and SCSS bundling.
After placing the folder in your WordPress themes, you then:
Alternatively, you can run npm run preview and that will both start the watch task and start a proxy server running on localhost:3000 that will automatically refresh the browser anytime you save a change. In order for this feature to work you will need to change the domain in package.json on line #8. In my file it mentions myexample.local but obviously you will have a different local dev domain that you want to proxy.
Enjoy!