In 2019, Sonsie made his NAB League debut, playing top level junior football for the Eastern Ranges at age 16, including in the side's grand final loss.[5] The same season he was selected to play national representative football for the Victorian Metropolitan Under 16s side, where he earned MVP honours as the team's best player in its national championship winning run.[6]
The impacts of the COVID-19 pandemic saw the 2020 junior football season cancelled entirely.[5]
In the lead in to the 2021 season, Sonsie was projected by AFL Media and ESPN as a likely top five pick in the forthcoming AFL draft.[5][7] During the year he played junior representative football with the Eastern Ranges, top level exhibition games for the AFL Academy side and made his VFL debut for Box Hill where he starred with 24 disposals and two goals.[2] At the end of the NAB League season, he was rewarded with Team of the Year selection honours in what was a partially COVID interrupted season.[2][8] Despite occasional starring performances, Sonsie's draft ranking progressively fell over the course of the season, as pundits considered his output uneven and inconsistent.[9][10]
Across his junior career, Sonsie was lauded for his ability to play inside and outside of midfield stoppages and his disposal accuracy.[11]
Immediately prior to the AFL draft, Sonsie was projected to be taken with the 17th and 23rd picks by AFL Media and ESPN, respectively.[12][13]
Sonsie was drafted by Richmond with the club's third pick and the 28th selection overall in the 2021 AFL draft.[14]
He made his debut in Round 18 of the 2022 season and held his spot for the remainder of the season, as well as in the club's elimination final loss to Brisbane.[15][16] He played a total of seven AFL games that season.[17]
In Round 22 of the 2023 VFL season he was suspended for three weeks after violently punching North Melbourne's Tom Cappellari in the head. [18]
