All CMS components provides a way to define concrete template for conrete usage on a concreate instance. This enables to optimize loaded data from DB and geneted HTML to match actual requirements.
CMS includes many standardized modules for solving standard solutions. If your web needs something different, CMS provides module of user defined data structures. So it is easy to declare data structures through UI in the CMS that matches needs of your web.
This module opens oportunities to use the CMS not only for public websites, but also for data entry line of business applications. It doesn't matter what you need to manage, the CMS can provide data structures and UI for it.
Years of CMS usage brought many standardized modules.
Integration with Bootstrap UI library gives ability to create standardized administration interface, but also gives basics for responsive public websites.