An example of this is the famous Mexican painter and muralist Diego María de la Concepción Juan Nepomuceno Estanislao de la Rivera y Barrientos Acosta y Rodríguez (AKA Diego Rivera, 1886-1957). Some biographical information is here and more detail regarding his early career is here.
Rivera came from a well-to-do family and was able to study art both in Mexico and in Spain. From Spain he went to Paris to joint the modernist art scene there. By the early 1920s his politics had solidified into Marxism. He was became a Communist Party member, but was cut loose because his sympathies were with Leon Trotsky rather than Stalin. However, he remained a strong "fellow traveler" for the rest of his life.
Below are examples of Rivera's painting over his career. Some of the stylistic evolution was due to normal maturation -- sloughing off earlier styles for different ones. Also, his work was influenced by stylistic fashions of the inter-war years. Whereas he experimented with abstract art in Paris, by the time he returned to Mexico Rivera had settled into a slightly stylized form of representational art suited for his propaganda murals.
For what it might be worth, I prefer the pre- Great War art to his later works.
This is a nice painting: note the triangular element of the composition.
A touch of cubist faceting here on the figures, but it works well.
The whiff of distortion adds interest to this portrait.
Rivera had a good command of the human figure when he chose to use it. The pose of the central figure is unusual, but effectively done.
Stylized, and very 1940s. A far cry from his paeans to the proletariat: Rivera must have been bought one way or another here.
A stereotypical propaganda scene.
The lower part would have made a nice 1928 Vanity Fair magazine cover illustration.
Little overt propaganda here, but this represents the mature Rivera style.
A late mural-on-canvas dripping with antiAmerican hostility and general ugliness typically found in political art.