Country tag for Australia is:
AST
If you want play for Australia HOI4 you could use tag command:
tag AST
To annex Australia in HOI4 you could use annex command:
annex AST
To delete all Australia units you could use deleteallunits command:
deleteallunits AST
To add interests on Australia you could use add_interest command:
add_interest AST
To remove interests on Australia you could use remove_interest command:
remove_interest AST
To start occupation on Australia you could use occupationpaint command:
occupationpaint AST