Was Isabella d'Este an Italian duchess?

Question

i couldn't really find it on the internet.

Answer 1

No.  She was a  marchioness or a marquise.

Her younger sister was the Beatrice d'Este, Duchess of Milan as consort to Ludovico Sforza.

Answer 2

Isabella d'Este (18 May 1474 - 13 February 1539, death at 64 years old) was marchesa of Mantua and one of the leading women of the Italian Renaissance and a major cultural and political figure.

Born in Ferrara, she was the first daughter of Ercole I d'Este, Duke of Ferrara, and Leonora of Naples, daughter of Ferdinand I of Naples, the Aragonese King of Naples, and Isabella of Taranto.

At the age of 16 she was married to Francesco Gonzaga, Marquis of Mantua. Her younger sister was the equally famous Beatrice d'Este, Duchess of Milan as consort to Ludovico Sforza. Isabella was related by birth or marriage to almost every ruler in Italy and is known as "The First Lady of The Renaissance". She was also known as "The First Lady of the World" and "La Primma Donna."

In short, Basically yes