You Do Need power plug adapter while traveling from Czech Republic to Bhutan.

Here is Why You Need An Adapter

The outlet and plug type used in Bhutan are C, D and G and in Czech Republic are C and E. This is how they look like.

Czech Republic

In Czech Republic, outlets of type C and E are in use.

Type C

Type E

Bhutan

In Bhutan, outlets of type C, D and G are in use.

Type C

Type D

Type G