Let us return to the proud tradition of walled cities.
Aside from the obvious don't zone floodplains I don't really know what we're supposed to do about this. Australians significantly resist densification of cities and don't plan cities well at all which reenforces that resistance. We're absurdly highly urbanised but in a sprawling manner.
We can't really reduce bushfire danger much without massive deforestation so let's not do that. It's not really plausible to like build underground and stuff in the regions/rural areas.
There's stuff we can procedurally get better at but floods and fires aren't like earthquakes where you can build structures that are basically untouched.
Are we just fucked?