Yo! It'll affect your ATAR in as much as ranking contributes to your overall scores, but:
(a) results from one subject in isolation shouldn't make a
drastic difference (depending on your interpretation, I guess - play around with the ATAR Calc if you're interested); and
(b) as difficult as it might be, thinking about it too much probably won't help.
If you're keen to know more about how much rankings and stuff affect you, Jamon did a really great live-stream the other week, which you can
watch here.
