I recently stumbled upon a post in /r/scificoncepts which talked about Dark energy prisons. (https://www.reddit.com/r/SciFiConcepts/comments/nd11sd/dark_energy_prisons/)
To increase the expansion of the universe, dark energy must overcome gravity. This is why galactic bodies are getting further and further away from us whilst celestial bodies within our galaxy are not. However, if dark energy can be manipulated by technology, then it can be used to expand a region of space between two objects.
With sufficient power, one could increase the expansion of the universe at a rate faster than the speed of light. This does not affect causality much in the same way as the Alcubierre drive. However, instead of shrinking space, it is using dark energy to expand space. Thereby making it impossible to travel across those distances. Once there is sufficient emptiness between the two objects, the background dark energy would be more than enough to keep the two objects away from one another forever.
The stronger the gravity between two objects, the more dark energy would be needed to overcome it. So, using it within a solar system would just be a waste of energy. However, on an interstellar scale, the gravity could be weak enough to be worth expanding regions of space for your own use.
Dark energy would be utilised to separate two objects from one another. This could either be used against an antagonistic force or as a way to defend oneself against other forces in the universe. Nevertheless, it would be a unique way to isolate civilisations from one another.