You Do Need power plug adapter while traveling from American Samoa to Cocos (Keeling) Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Cocos (Keeling) Islands is I and in American Samoa are A, B, F and I. This is how they look like.

American Samoa

In American Samoa, outlets of type A, B, F and I are in use.

Type A

Type B

Type F

Type I

Cocos (Keeling) Islands

In Cocos (Keeling) Islands, outlets of type I are in use.

Type I