Yes, in general it's a combination of both decisions you make in terms of going in to a specific scenario, and then what scenarios are available and how severe they are based on what is going on in the solar map. And then the effects of whatever happens in the scenario reverberates back out into the solar map. There are also procedural randomized elements within the scenarios, independent of anything other than just an RNG.
These scenarios aren't large, or long, in the main. They're interesting, to-the-point microcosms of the main larger game. There might be hundreds of ships flying around and the tactical situation is complex in the sense of you deciding what to do, but you won't spend more than 5 minutes executing your decisions in most cases. Too long in particular tactical instances makes it hard to keep in mind all that is going on on the solar scale.