There's a number of videos on junior grade Aussie NRL and rep teams and they aren't amazing.
They’re not small either.
People act like Aussie kids are all Jono Thurston sized battlers which just isn’t true. Tom Turbo made his peer group look like they hadn’t hit puberty. Klemmer was always biggest kid on the field regardless of who he was playing.
If you want to see under-sized footy teams check out a Northland, Waikato, or Mid Central age grade rep team.
These are Harold Matt’s teams, and these kids are all big for their age.