Since the essay will be solely assessing the Operations topic, you may be required to explore concepts within any subtopic, or a combination thereof. This means that your preparations should be extensive and cover all subtopics, allowing you to maximise your readiness.
With that being said, influences, processes and strategies tend to be assessed more frequently than role. For example, Question 27 from the 2019 Business Studies HSC exam required a response targeting operations strategies specifically:
Analyse the relationship between performance objectives and operations strategies.
To supplement your preparations, I suggest attempting Operations essay questions from the following resource:
A series of Section IV questions to assist you in your preparations for your Business Studies exams Keep in mind that you need to incorporate relevant case study material within each question to effectively support your response. All the best...
boredofstudies.org
I hope this helps!