Question

Suppose there's a model with 2 constraints originally. Now that another constraint is added. Which of the following are possible:
1) feasible region shrinks
2) feasible region stays the same
3) feasible region expands

and

Which of the following are possible:
1) optimal value in target cell decreases
2) optimal value in target cell stays the same
3) optimal value in target cell increases

I think the answer is 1) for both questions, but I want to ask do they hold in general? Or is there some exceptions?