You Do Need power plug adapter while traveling from Switzerland to Congo.

Here is Why You Need An Adapter

The outlet and plug type used in Congo are C, D and E and in Switzerland are C and J. This is how they look like.

Switzerland

In Switzerland, outlets of type C and J are in use.

Type C

Type J

Congo

In Congo, outlets of type C, D and E are in use.

Type C

Type D

Type E