It is not possible to get extensions on any visa.
Each visa has an expiry date, and if you haven’t lodged an application for a new visa, or been granted a new visa, you will become unlawful once your visa expires. If the expiry date on your visa is getting close you should apply for a new visa (if that is possible …and you’re eligible). Also seek out expert advice about your visa pathways from a Registered Migration Agent, because you may find that there are very limited options and becoming unlawful after your visa expiry has significant (negative) consequences (see Q&A earlier herein).
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