This is a really important question but a very complicated topic that can’t be fully explained here.
Here are some links to give you more information about it.
One way to see if a building has any type of combustible cladding or been issued any notices is in the vendors statement in the contract of sale. It may be a certificate or noted in the minutes of the owner’s corporation AGM. The selling agent may have some knowledge and had discussions with the OC about it so ask them about it.
The councils and state government have assessed thousands of buildings in Victoria but there is no public register that you can check so not only is the entire issue around combustible cladding complicated, the difficulty for a buyer to find out if an apartment or the building has an issue with it is also complex.
This is also not something you can engage an expert on to assess the building. The most knowledgeable source of information with be the OC manager for that specific building. As a buyer you don’t have access to that information so if the Agent doesn’t already know then ask them to make enquiries with the OC on behalf of the owner.