No , just needs to be on a Dr's letterhead , and have that you have tested negative to the " Covid 19 virus based on a Rt-pcr result , and in his opinion you are fit to fly ( travel overseas )
If you mean with regards to a travel exemption from dept of home affairs , as long as you state you will be overseas longer than 3 months , then yes ..
leaving Australia you have to get an exemption from Dept of Home Affairs...reason to leave that most people use are to visit spouse's or will be overseas for more than 3 months ...either way they will need an exemption at this stage
then their best option is to go to the Embassy website ...all they need to know and more .. as for the actual travel part , get to the airport and follow orders ...that's it
If you picture the amount of times you walked out thru customs and the first thing you see are Chinese tourists playing Follow the Flag ", then thats what its like ...being led from check to check , then finally released on floor 2 at your quarantine taxi pickup ...all seamless and controlled ...