An essay is supposed to answer a question, right? Yes. That much you probably already know.
That means your basic essay format has to be something close to this:
Say what problem needs answering.
Say your answer.
Add background if you need to.
Lay out proof, in stages.
Refer to the problem again quickly, and say your answer again.
This schematic layout works everywhere.
Want to see what it looks like in real life? Here are the first lines of each of the paragraphs of an actual essay built like this (and it got a good grade):
‘What’s the best evidence that pre-carboniferous plants and animals colonized the land in partnership? Coprolites: petrified feces, great caches of crap which exist in the United Kingdom and eastern Europe.
Most of the droppings contain undigested land plant spores and a mass of transport tubes and cuticle.
A clue about what the animals were like is traces of plant responses to injury.
How the predators ate-that is, by chewing or sucking-suggests how they looked.
Was it enzymes or simple diffusion by which Silurian guts profited by a diet of spores?
Did they always eat from the vine, so to speak, or were they also litter-feeders?
On the evidence of the non-animal fossils, how big were the animals themselves, and what may they have looked like?
This all squares with the direct fossil record.’
See? You can tell just from the first lines of the paragraphs what the essay shows, and how it shows it. This is a standard way of doing things because it’s utterly practical.