Hi miyukiaura,
I think this could be a bit controversial because a lot of people say not to pre-plan essays because essay topics are all 'unique', but I think so long as you are flexible and modify them to fit the prompt it's a way of surviving. In found it helpful for me, who couldn't think up things on the spot.
It's easier to show than explain:
eg. what I did
(https://i.imgur.com/lJNHPy2.png)
Basically write down all the possible themes that essay topics could revolve around, then plan 3 ideas of possible themes/topic sentences for body paragraphs. I colour-coded paragraphs that were similar that I could kind of squish into multiple themes of essays. Again, you still have be flexible enough to make sure you are answering the essay topic, but if you've written enough practice essays on a range of topics you can kind of take paragraphs (or parts of them) and fit them into similar essays. Also you can add quotes/evidence you want to discuss in the table too.
Hope this helps!