The easiest way historically is to use a combination of grants and tax breaks. ABC used to pump out some amazing content but sadly the network had a huge amount of its funding continuously stripped over the 12 or so years that we had libs in power federally. At the very least they really need to specify the sort of content that they want to mandated because "More Australian content" is incredibly vague and as I mentioned inevitably leads to more reality garbage getting pumped out.

Either way, the government is attempted to fix this issue without spending money which just isn't an effective way to reach desirable outcomes with respect to encouraging quality content.