You Do Need power plug adapter while traveling from Iran 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 Iran are C and F. This is how they look like.

Iran

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

Type C

Type F

American Samoa

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

Type A

Type B

Type F

Type I