You Do Need power plug adapter while traveling from Sri Lanka to Western Sahara.

Here is Why You Need An Adapter

The outlet and plug type used in Western Sahara are C and E and in Sri Lanka is G. This is how they look like.

Sri Lanka

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

Type G

Western Sahara

In Western Sahara, outlets of type C and E are in use.

Type C

Type E