What do you have to do to make the wing flex and extend?

To make a wing flex and extend, you typically manipulate control surfaces such as flaps or ailerons, which are connected to the wing structure. In some aircraft, wing flex is also influenced by the aerodynamic forces acting on the wing during flight, as well as structural design that allows for flexing under load. Additionally, using hydraulic or mechanical systems can adjust the wing's position for takeoff, landing, or maneuvering.