Examples include ‘distortion, exaggeration, primitivism, and fantasy and through the vivid, jarring, violent, or dynamic application of formal elements’ to create a sense of ‘highly subjective, personal, spontaneous self-expression’. 

(Source – https://www.britannica.com/art/Expressionism) 

(Illustrated examples:) 

‘Evening on Karl Johan Street’ 

Painting by Edvard Munch 

‘The Yellow Cow’ 

Painting by Franz Marc