When you study a model answer, there are two things to look at: its structure, and its vocabulary.
The common mistake
If you rewrite that same model, memorising its vocabulary and its structure, what you have learned is how to produce that one essay. Which is close to useless.
Because in the exam, the question will not be that question.
What to do instead
Take the model, learn the structural frame, learn its useful phrases. Then write a similar but not identical question.
A concrete example
The model is about electric cars:
There is an increasing number of people who opt to use battery-powered cars, because they think it's going to minimise the impact on the environment. On the other hand, a lot of people think battery recycling poses a huge problem.
From this you can take:
- Topic vocabulary: battery-powered cars, minimise the impact on the environment, recycling poses a problem
- Linking phrases: on the one hand, on the other hand, in general
- The argument frame: state the trend, give the case for, give the drawback
Now write a different question using that frame
The government is increasing spending on subsidising the development of electric cars. What do you think about this?
Same subject area, same vocabulary set, same argument frame, different question. Now you are forced to use what you just learned rather than reproduce it.
That is what learning looks like.