Like all wars, they will be fought with weapons not today developed or understood. It might be lasers. It might be something that harkens back to the day when lasers were thought to be cutting edge technology.
If man ever takes up residence in space, the question is not what weapons he will use but can man find a way to live in space without fighting a war there. History does not speak well to that possibility.
I’d have to say that it all depends on the target. After all you can fling a rock at a space station and destroy it. The “Rod from God” is basically a tungsten telephone pole launched from space at a ground based target. It comes in at hypersonic speed and delivers some serious energy that way.