Glenn Maxwell is at No.3 spot. His best score i.e., 145, which came against Sri Lanka is 2016, carries 4th place in the list of highest individual scores.
Source: BCCI
Hazratullah Zazai is number second in the list. He scored 162 in just 62 balls in a T20I against Ireland in 2019
Source: AP
Former Australia Captain, Aaron Finch has the 3rd highest as well as the highest individual T20 score to his name. The player scored 156 in 2013 and 171 in 2018.