How does it work if I'm not adding features, but want to refactor my code bases? E.g., the OOD is poor, and I want to totally change it and split the codes into

How does it work if I'm not adding features, but want to refactor my code bases? E.g., the OOD is poor, and I want to totally change it and split the codes into new files? Would it work properly as it requires extensive reads + create new files + writes ...