J.J. Abrams has opened up about the process of developing Rey’s character in the sequel trilogy, explaining that he had a long term plan for her, but that the details were more “shapes in the fog” rather than an elaborate roadmap. He also admits that parts of her planned story arc had to be adjusted as the saga continued to expand.
In an interview with IGN, the director of The Force Awakens and The Rise of Skywalker discussed the completion of Rey’s arc in Episode IX, explaining how he carried ideas forward from his original plan established during The Force Awakens, even though ultimately they were only “building blocks” to manage plot points.
Source: IGN.com Was Rey's Arc in Rise of Skywalker Part of JJ Abrams' Plan All Along?