Apsley Falls is the easiest big reward near Walcha, about 20 km east of town in Oxley Wild Rivers National Park. The river drops into a steep-walled gorge, with lookouts and picnic facilities close enough to the car park that you do not need a serious walk to feel the scale.
The longer Oxley Walk gives better angles into the gorge when conditions are good. Bring water and check closures, especially after storms, floods, or fire damage.