Sydney is about 1.9 times bigger than Cocos (Keeling) Islands.

Cocos (Keeling) Islands is approximately 14 sq km, while Sydney is approximately 27 sq km, making Sydney 91% larger than Cocos (Keeling) Islands.
Tip: This to-scale comparison of Cocos (Keeling) Islands vs. Sydney uses the Mercator projection, which distorts the size of regions near the poles.