You Do Need power plug adapter while traveling from Fiji to American Samoa.

Here is Why You Need An Adapter

The outlet and plug type used in American Samoa are A, B, F and I and in Fiji is I. This is how they look like.

Fiji

In Fiji, outlets of type I are in use.

Type I

American Samoa

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

Type A

Type B

Type F

Type I