I think you're referring to the black bar below comments that are too long which can be clicked to expand the comment?
That has nothing to do with KES's collapsible comments feature as someone else brought up. It's a native kbin feature.
KES actually has a feature that addresses this by automatically clicking that bar, but it seems to only apply to thread bodies, not comments, currently. If you're interested in having it apply to comments too, try filing a new issue on Github requesting the feature. The mod in question is "Always expand post bodies" in the Threads category. This should be fairly easy to add.