Yeah, for some reason or another that I personally fail to understand, there is always this consensus that the only way to do really well in the HSC is by choosing extremely hard subjects (like extensions), so you can rely on their scaling to get you over the line.
I for one know this isn't true, as I know many people who've succeeded without choosing all the "hard" subjects, but picking subjects which "THEY ARE GOOD AT". Here is a Matrix article you can read:
https://www.matrix.edu.au/scored-atar-99-95-without-maths-natalie-buckett/
If you lock out all this external obsession of choosing hard subjects, and just think logically about what is good for yourself, you'll realise that if you pick hard subjects that you know you aren't capable of doing (or have no interest in), you'll fail to find the motivation of preparing for them throughout the year (or you might just not understand the concepts to the required degree). And as scaling only works once you get past a threshold mark, studying a HSC subject that you don't find doable would mean you may fail to reach even that, so there goes your scaling out the window. Or your decisions may back fire, and you may be scaled DOWN.
Choose the subjects you're good at, and, to answer your question, to get a 96+ all you need to do is work hard. The reason scaling is present in the HSC is because BOSTES aims to make each subject "equally hard", so that you're not at a disadvantage picking Maths Extension 2 compared to PDHPE. BOSTES know that not everyone is good at just Maths or Ancient History, so they equalise the playing field to recognise your unique talent. So apart from that (incorrectly derived) phobia/obsession that you gotta take the hard subjects to succeed, there is virtually no reason for you to pick subjects that you think are hard.
Hope this helps and good luck with your studies