Ive had a look at the legislation, its an ammendment to an existing set of laws. It underwent some changes as it passed through the House of Representatives and the Senate, so i had a look at the 'As passed by both houses' version at https://www.aph.gov.au/Parliamentary_Business/Bills_Legislation/Bills_Search_Results/Result?bId=r7284
So it looks like what is 'Social media' can be defined by a Minister / Commissioner, it looks like there needs to be something documented by the entity to prevent underage users(again not calling on lemmy.world to do something for this as part of this post) by the Social media company, and it looks like the recording of government id's for the purpose of confirming ages is expressly prohibited.
A penalty Unit is around $300.
The law specifically mentions government IDs in the legislation . If(edit:i'd) have to check, but Im confident they're specifically excluded.