Hey there!
It's definitely possible! Big 4 firms often have global networks, so moving within the company is feasible, though it depends on specific circumstances and the business needs. While it’s true that some Big 4 companies may be hesitant to hire international students for entry-level roles due to visa complexities, there are still instances where they do hire students on OPT, particularly if the candidate has the right skills. One of my friends did it this way - that's why I know about it :)
I'm not sure if this fully answers your question, but I hope it helps! If you have any further specifics in mind, feel free to clarify.
BR Alessa :)