Q.Kangaroo paw and gardenias
Can kangaroo paw and gardenias be grown together in a full sun flower bed?

Kangaroo Paw are hardy in zones 10-11. Gardenias are hardy in zone 8-11.
The first question you need to answer is if you are in the correct growing zones.
Kangaroo will need a near full sun location and Gardenias will need a partial shade location.
These links will help you.
https://www.gardeningknowhow.com/ornamental/flowers/gardenia/gardenia-plant.htm
https://www.gardeningknowhow.com/houseplants/kangaroo-paws/kangaroo-paws-houseplant.htm