She didn't consider herself one, but her actions suggested otherwise
Her views on feminism are not known
Answer
Yes, in her own way. Although she never used the term "feminist", she was a strong advocate for women's rights and believed that women were just as capable as men. She wrote about the importance of education for women and argued that they should be allowed to participate in all aspects of society.
The Marvelous Mind of Margaret Cavendish:
An Engaging English Quiz on the Duchess of Newcastle-upon-Tyne