Nah don’t stress, it’s too late to be stressing now anyway and it’s not that important.
If you have any practice essays from your teacher or whatever then go read them and try to pick out what they’ve said about the authors message - that way you’ll at least have some analysis in your essay (so long as it’s at least a sort of similar topic).
The most important thing to remember is to relate it to the prompt. You’re better off having a bad essay that’s completely relevant than an amazing essay that’s completely off topic. Make sure you spend time planning it.
Google your texts now and have a look at what there is about symbols or author techniques or whatever in the text. Remember a few of these techniques (pick ones that are fairly generic) and then you should be able to incorporate them into your essay no matter what the prompt is.
Memorise a few quotes that you think you will be able to use for any prompt (so like super generic things, things like support, fighting for a cause, things like that tend to be common themes that pop up).
There’s really no point stressing about it now. Just plan it well and try and stay on topic as much as possible.