Pivot diagram of a Class 2 lever
Different classes of levers are identified by the way the joint and muscles attached to the bone are arranged.
For the Class 2 lever the load is between the pivot and the effort (like a wheelbarrow). The effort force needed is less than the load force, so there is a mechanical advantage.
Standing on tip toes is a Class 2 lever. The pivot is at your toe joints and your foot acts as a lever arm. Your calf muscles and achilles tendon provide the effort when the calf muscle contracts. The load is your body weight and is lifted by the effort (muscle contraction).