what is the recommended minimum hours of sleep for a 3 year old

Red Nose does not have any specific information in relation to amount of sleep appropriate for each age range of babies/children.

Raising Children Network does provide this information
https://raisingchildren.net.au/toddlers/sleep
https://raisingchildren.net.au/preschoolers/sleep

Also refer to:
WA Child & Adolescent Health
https://cahs.health.wa.gov.au/Our-services/Community-Health/Child-Health

Ngala
https://www.ngala.com.au/