How to find your essay's target audience?

Just ask yourself, who you are presenting it to. Or who are you trying to persuade. For example: if I’m taking about the environment and how we need to save it. It can go either one or two ways. You can pitch your idea to someone who already known what your talking about and you can offer a better solution OR you can inform a new audience who isn’t knowledgeable on the subject. It just depends on what you want to write about