You Do Need power plug adapter while traveling from South Sudan to Brunei.

Here is Why You Need An Adapter

The outlet and plug type used in Brunei is G and in South Sudan are C and D. This is how they look like.

South Sudan

In South Sudan, outlets of type C and D are in use.

Type C

Type D

Brunei

In Brunei, outlets of type G are in use.

Type G