McKenzie grew up in Lightning Ridge, New South Wales, a small outback town roughly 700 km northwest of Sydney.

[2] According to ESPN journalist Brittany Mitchell, "McKenzie grew up with the Steeden in her hands as opposed to the Gilbert", referring to the fact that she was "a rugby league fan from a young age who dreamed of playing for the St George Dragons."

She was inspired to switch to union after watching TV coverage of the Australia women's sevens team's gold-medal run at the 2016 Summer Olympics.

[18] McKenzie served as a care worker for What Ability, an Australian disabilities service that uses sportspeople in that role, from 2020 until leaving for New Zealand to play in the inaugural 2022 season of Super Rugby Aupiki.

He doesn't know who I am or what's going on and his level of autism is pretty severe, so it's just cool to hang out with him and do fun things like go to the beach hangout, cafes, chill and he's just changed my perspective on life.