Only two seasons
According to IMDB and Netflix there are four seasons.
https://simkl.com/tv/751254/chilling-adventures-of-sabrina
Netflix has 4 parts but only 2 seasons.
The first half of the first season, consisting of ten episodes, was released on October 26, 2018. The series received positive reviews, with critics praising Shipka’s performance, as well as the premise, visuals, and directing. A Christmas special episode was released on December 14, 2018, and the second half of the first season was released on April 5, 2019, consisting of nine episodes. In December 2018, Netflix renewed the series for a second season consisting of 16 episodes, split into two equal parts, of which the first eight episodes were released on January 24, 2020, with the second set released on December 31, 2020. In July 2020, Netflix cancelled the series.