You Do Need power plug adapter while traveling from Mexico to Peru.

Here is Why You Need An Adapter

The outlet and plug type used in Peru are A, B and C and in Mexico are A and B. This is how they look like.

Mexico

In Mexico, outlets of type A and B are in use.

Type A

Type B

Peru

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

Type A

Type B

Type C