Acknowledging the other side of the topic is a great way to show nuanced analysis in your essay. Usually, when you get a prompt, you won't be fully agreeing or fully disagreeing with the prompt. It will be more like you 3/4 agree and 1/4 disagree, or vice versa. One thing you should be careful of when including the rebuttal paragraph is that you aren't contradicting your contention. It's more of a 'I acknowledge this, but this is why the other side is correct' or a 'challenge' paragraph.
For example, let's say the topic is 'Rainbows are the most beautiful phenomenon observed in the sky' and we are disagreeing with this. You can acknowledge the other side by saying: Whilst rainbows are beautiful due to the many colours it depicts, its common occurrence reduces its aesthetic - making other phenomena, such as an eclipse, far more enthralling.
This was a really simple example, but I hope you get what I'm saying! Including phrases like the above will show the examiner that you are constantly thinking about the opposing side of the prompt, whilst substantiating your own stance.
P.S. I'm only in year twelve, so if someone could weigh in that would be great!