Your HSC marks and ATAR, if high, can serve as qualification if you're seeking a tutoring job (say at a tutoring company). That's how I was able to work in a tutoring company throughout 2020.
I think it all depends on what kind of part-time job you're seeking. Retail may not require any kind of qualifications (although previous experience might be required, but some don't mind those with no experience and are willing to train them). I was accepted and started working at Woolworths a couple of days ago, despite not having any retail experience.
If you're looking to work in something like, say, office administration/reception, there are some TAFE courses that run for short periods of time and can improve your employability upon receiving your certificate.
Additionally, universities like USyd offer a range of short courses which can be of benefit depending on the job you're seeking.
Home page
cce.sydney.edu.au
I hope this helps!