It matters for each candidate, because no matter what they say they want or what they would do, if they have to get legislation passed to do it, I think you rationally have to take that into account given the lower odds such a thing might come to pass.
That's one reason, for example, the Harris attack on Trump about a national abortion ban is stupid. First, he doesn't even want to do that, and second, he can't do it on his own. That's a legislative issue, not an executive one. I'm sure some of the things Harris has said she wants to do fall in the same category.