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

Here is Why You Need An Adapter

The outlet and plug type used in Greenland are C, E, F and K and in Sri Lanka is G. This is how they look like.

Sri Lanka

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

Type G

Greenland

In Greenland, outlets of type C, E, F and K are in use.

Type C

Type E

Type F

Type K