You Do Need power plug adapter while traveling from Sierra Leone to Vatican City.

Here is Why You Need An Adapter

The outlet and plug type used in Vatican City are C, F and L and in Sierra Leone are D and G. This is how they look like.

Sierra Leone

In Sierra Leone, outlets of type D and G are in use.

Type D

Type G

Vatican City

In Vatican City, outlets of type C, F and L are in use.

Type C

Type F

Type L