Can Drupal-based sites be easily extended or expanded in the future?

In short: yes, and without much effort.

As an open-source platform, Drupal allows anyone to modify it, extend its functionality or add add-ons at any time.

Speaking of add-ons, Drupal is heavily add-on based. As such, you can easily extend Drupal’s functionality by installing any of the 44,000 free add-ons available. If the functionality you need is not found within the available add-ons, we can easily create a custom-made add-on specifically for your project. These add-ons, for example, can account for additional integrations with your already existing systems.

Last, but not least, Drupal is highly lightweight and scalable. As such, it can grow in-line with your business.