Definitely! In fact, the experience of sitting them in Year 12 makes it more likely that you will do better in Year 13. Be aware that for some subjects, particularly Physics, Chemistry and Calculus, you need knowledge of the subject at Level 3. However there are other subjects, like Geography and English, that are a lot more about how you engage with resource material and how well you can write. So it is certainly possible to do Scholarships in year 12, and even more so if you are taking those subjects at Level 3.