You need to have  a few programming chops to benefit from this but OpenAI have posted on GitHub (Now taken over by Satan) an app that allows you to tweak expressions.
https://github.com/openai/glow

"The org has releaseda reversible generative model, called Glow, describedhere with open-source codehere. It can be used to, for instance, tweak things like smiles,signs of age, eye size, and hair color, in photos of faces." El Reg.