You Do Need power plug adapter while traveling from Sierra Leone to Balearic Islands.

Here is Why You Need An Adapter

The outlet and plug type used in Balearic Islands are C and F 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

Balearic Islands

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

Type C

Type F