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

Here is Why You Need An Adapter

The outlet and plug type used in Thailand are A, B, C and O and in Vatican City are C, F and L. This is how they look like.

Vatican City

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

Type C

Type F

Type L

Thailand

In Thailand, outlets of type A, B, C and O are in use.

Type A

Type B

Type C

Type O