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

Here is Why You Need An Adapter

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

Western Sahara

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

Type C

Type E

Sri Lanka

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

Type G