Are allegory or satire aesthetic features?

This is somewhat a matter of perspective, but I would say no. I would argue that both allegory and satire are generic elements. They are less about the style and aesthetic feel of a piece and more about what type of piece this is. In the case of Animal Farm, this is a satire in that it mocks and attacks the rise of the Soviet Union. It points out the hypocrisy of how those in power abuse political ideals for their own advantage. The novel is also an allegory in the sense that most elements of the novel have direct comparisons in history. For example, Napoleon is Stalin, Snowball is Trotsky, etc... These are generic elements; they tell us what type of book Animal Farm is.

Aesthetic elements are more stylistic, and describe how the book expresses these themes. For example, Orwell's short, simple sentences would be an aesthetic feature.