There is no point at which it expands. The radius of a black hole is proportional to its mass. As the hole radiates energy to infinity, it loses energy and thus mass, so its radius shrinks. It remains a black hole.

At some point the hole becomes so small that we don’t understand what happens because describing it would require a theory of quantum gravity and we don’t yet have one that is widely accepted. So perhaps something weird happens at the very end when its radius is on the order of the Planck length.

There is no point at which it expands. The radius of a black hole is proportional to its mass. As the hole radiates energy to infinity, it loses energy and thus mass, so its radius shrinks. It remains a black hole.

You can find some (crude) formulas and calculations in this other answer.

At some point the hole becomes so small that we don’t understand what happens because describing it would require a theory of quantum gravity and we don’t yet have one that is widely accepted. So perhaps something weird happens at the very end when its radius is on the order of the Planck length.