How to achieve this painting effect?

The two images seem pretty different to me so they might need different approaches. 

In the one with the frontal eyes the white »background« could be achieved with Brushes (or stock or ai …) on a Layer Mask for example. 

As for the painterly effects you could do a search for Watercolor Actions but you could also use Firefly/Generative Fill to edit an image (if the pixel limitations meet your ultimate output needs). 

Could you post (part of) an image you want to edit thusly?