Most Student visa (subclass 500) holders carry condition 8202: you have to maintain enrolment in a registered course at the same level (or higher) as the one your visa was granted for, and you have to be enrolled in a full-time, CRICOS-registered course.
That leaves room to change institution, campus or even field of study without automatically needing a new visa — but it depends on the level of the new course, whether it's a genuine continuation of your study plan, and how your provider reports the change to the government.
Before you sign anything with a new institution, talk to a registered migration agent about whether your specific change stays within your current visa's conditions or requires a fresh application. Getting this wrong can affect your visa validity, not just your enrolment.