I'd definitely expect a few special aircraft arrivals...
Not special but Vietnam Airlines 787 VN-A868 is expected in Sydney from Canberra Friday morning as VN1.
Here's a list of the member states :
https://aseanaustralia.pmc.gov.au/asean-australia/about
I've heard talk that we will see the Brunei Government 748BBJ :
https://www.planespotters.net/photo/...ing-747-8lqbbj
Cambodia has an a320 :
https://www.jetphotos.com/photo/8327119
Indonesia has a 737
https://www.planespotters.net/photo/...ng-737-8u3bbj2
After a few google searches it appears the Laos president travels around on a Laos airlines a320 :
https://www.planespotters.net/photo/...irbus-a320-214
Malaysia has an a320CJ
https://www.planespotters.net/photo/...214cj-prestige
Myanmar Air Force has two Fokker 70's, Here is one :
https://www.jetphotos.com/photo/8777410
Thai Government a340-500 is hotly tipped to be attending :
https://www.planespotters.net/photo/...irbus-a340-541
Singapore president has apparently been getting around in a VH registered Gulfstream :
https://www.jetphotos.com/photo/7801601
Phillipines is apparently not in attendance.