By painting their face like a certain animal (real or mythological), they gain that animals capabilities and skills. For example, painting their face as a butterfly would allow them to grow wings and fly. Depending on how well they know a specific person, if the user paints their face to look like them, they can copy their characteristics such as their voice, skills and their quirk (if they have one.)

Quirk Type - Transformation

Best suited for - Generalist (There's so many different aspects of this quirk, I can't categorise them 💀)

Drawbacks - Any paint that touches their skin will eventually sink into the user's skin, and once the paint has sunk in, they will lose the abilities and their face may feel dry and itchy, depending on how much paint they used.

Possible Hero/Villain names -

Artist
Face-Stealer (I just watched the live action ATLA leave me alone 😭😭)
Swatch
Morphe/Morphra

This sounds good for like an art oc and tbf who doesn't like face paint