They are going to try their damnedest, I’m sure of that. But the logistical feat of actually denying all Americans their chance to vote is beyond their means. They will, at best, disrupt voting where they will see the greatest impact. States will conduct their elections as usual. Only Congress has the power to decide the timing of elections. I don’t see them passing any new laws. No state depends on the federal government to carry out their electoral duties (so far).
After that, we get to see what kind of obstructive bullshit they have planned to keep elected officials from serving if they don’t want them to. I don’t know what they could do aside from force another shutdown, aside from outright physical violence, which is entirely likely but it still raises the questions of ‘by what means’ and ‘is that feasible’. If we were going to see political assassinations on a large scale, I imagine we would have passed that point by now.