Sosa's career began with Mercedes, before River Plate signed him in 2018.[4][5] The 2018–19 campaign saw Sosa become a senior member of the club's first-team, he made his professional career debut in a 2018 Copa Libertadores fixture with Racing Club on 29 August 2018; he featured for the remaining sixteen minutes as River Plate won 3–0.[1][6][7] He ended the aforementioned season with five total appearances.[1]