Being ranked first in a subject is the best position that you can be in, as that will allow you to maximise your Assessment Mark, which is the mark that you receive that reflects your internal performance and contributes half of your overall HSC mark in the subject. In your case, maintaining your rank in English Extension 1 will mean being in an optimal position as you approach this subject's HSC exam.
On the other hand, a low rank in English Advanced may reflect poor internal performance in this subject. However, whether this applies to you, and the extent to which it may, depend on the academic capability of your school cohort. Placing low within a low-performing cohort typically implies a lower performance standard compared to placing low within a high-performing cohort. You should therefore check whether your school's English Advanced cohort is academically capable (you can also check the performance of your school's previous HSC cohorts), allowing you to better understand your current level of performance in the subject. In both cases, it is important to note that any rank improvement is encouraged as it will likely increase your chances of receiving a higher Assessment Mark.
Additionally, the extent to which your ATAR will be affected will depend on the units that end up counting towards it. Essentially, 10 units will count towards your ATAR, consisting of your best 2 units of English and your best 8 units across your other subjects. Since you are taking 3 units of English, you may have either 2 or 3 units count towards your ATAR, as follows:
- 2 units of English Advanced and 1 unit of English Extension 1
- 2 units of English Advanced
- 1 unit of English Advanced and 1 unit of English Extension 1 - In this particular case, the effect of English Advanced on your ATAR (whether positive or negative) will be halved because it would only contribute 1 unit towards your ATAR.
Of course, these combinations may depend on your total number of units.
I hope this helps!