Short answer: No limits with the right implementation.
Long answer: If you just use a view to move your character around, the limitation will essentially be the inaccuracy of floats in C++. When you're too far out everything will get jittery. But before yoi hit that issue l, you'll most likely run into other problems, such as storage.
If you want to get rid of the float issue, you could reset the coordnate system after a certain distance has been made.