Variation swatches can be displayed in three different shapes for different attributes. Follow the steps below to do that: 

1) From your WordPress Dashboard Menu, navigate to the Products > Attributes and get into your desired variation Edit mode.

2) Select any of the Attribute Shapes from three different shapes and click on Update. 

3) Now, refresh the Single Product Page or Shop Page to see the changes.

The final look would be something like this: