not all trials are harder than the hsc but id say most are. just depends on the school you go to. it would be possible for you to get maybe a 90 if you do really well in the HSC but i dont know bout 96.
its because your school rank is really bad so you likely have a tonne of grade inflation which makes i look like your marks are really good when in reality your marks will be adjusted down in the actual HSC to match your cohort's performance.