Generally speaking, you can achieve a high ATAR with any combination of subjects, as long as you can ensure you're performing to the best of your abilities across all your subjects (assignments and exams), which would require that you regularly study and stay up-to-date with relevant content. As mentioned above, taking English Advanced would be something to consider as it scales relatively well compared to English Standard, which might make your HSC English journey easier.
If you perform consistently well across all your subjects, however, the effect scaling will have on your final marks will most likely be minimal. When I did my HSC, I took English Standard as well as not so good scaling subjects like Business Studies and IPT and ended up with a 92 ATAR.
In year 12, your final mark for a subject is determined according to your assessment mark which contributes 50% to your final mark as well as your exam mark which contributes the other 50% to your final mark. Your assessment mark relies on your rank within your cohort, which will be determined according to your marks in your school assessments and how those compare to the marks of other students in your cohort (the higher your rank, the better your assessment mark can be). Your exam mark constitutes your mark in your HSC exam for each subject and strongly depends on your own performance.
I hope this helps!
