While your year 11 marks can indicate your level of performance across your subjects, which can subsequently be used to determine whether there may be a subject(s) that you should consider dropping as you get closer to year 12 (allowing you to have the best possible subject combination as you commence year 12), they do not contribute to your HSC results or your ATAR.
However, your year 11 results may be useful in terms of receiving early offers to study particular degrees as they may be treated as criteria for admission depending on the institution's early entry scheme. In terms of schemes available at most institutions, a prominent example is the
Schools Recommendation Scheme (SRS), which considers a student's year 11 studies in addition to other criteria.
Early entry schemes that are unique to a particular institution include:
I hope this helps!