You Do Need power plug adapter while traveling from New Caledonia to Sri Lanka.

Here is Why You Need An Adapter

The outlet and plug type used in Sri Lanka is G and in New Caledonia are C and F. This is how they look like.

New Caledonia

In New Caledonia, outlets of type C and F are in use.

Type C

Type F

Sri Lanka

In Sri Lanka, outlets of type G are in use.

Type G