@firewns – Striaght answer to the question is you either end up an Arahant or a Buddha. There is no half way change from a Sotapanna to a Buddha. As a Buddha needs to perfect the ten paramitas, which takes 100,000+ eons to perfect them.
You may want to read the Arhat and Bodhisattva: Roles and Aspirations with Reference to the Stages of Path for a better understanding of the training of both paths.
Hope this helps.
With metta, Seng Kiat