Do they have a lowest entry study score or something like that similar to ATAR?
If a course says 30 in EAL, can i still get in if I get like 27 or even 29
No if you don't meet the prerequisites (the study score) you are not going to receive an offer, even if you get the atar required, you need to meet the prereqs.
In the majority of cases, it’s exactly as stated above. I’ve only heard of one very rare exception: it was someone who had received a 24 raw for English (mainstream) for a course that required a 25 and otherwise had everything else e.g. ATAR. They were accepted because they had a lot of special consideration.
I wouldn’t rely on this exception and no matter if you’re in Year 12 or not, try to exceed 30 in EAL, through your exams (if you’re in year 12) or assessments (if you’re younger). Don’t give up and give it your best shot!