Express does not come packed with a huge bunch of built-in libraries to perform tasks that are beyond a basic website. Express is very minimal. But that does not mean that it is not capable of performing complex tasks.
You have a huge collection of Node modules on the npm registry that can be easily plugged in to your app and used for performing all sorts of tasks in the app.
In Chapter 1, What is Express?, we were introduced to Node modules, and we learned how to write them. We also found out that they can be used to modularly extend the power and capability of Express.
You could write your own Node modules to accomplish many things, but anything you are trying to achieve, probably there is an excellent open source Node module out there already. You just need to find the right module, install it, and use it in your app.