Lift up or tilt the recliner forward so that you have visual access to the rear underside of the the chair. You can rest the recliner forward on the top and the arms so that you have access.
Look on the left and right sides of the underside of the Natuzzi recliner. On each side you will see wingnuts, which can be adjusted.
Twist the wingnuts a quarter turn to make your tension adjustment. If you twist clockwise, it increases the tension and counterclockwise reduces the tension. You should reduce the tension if it is too hard for you to close and increase it if you are taller or heavier than the average person.
Sit the recliner right side up and try it out. You might need to make an additional tension adjustment to get it just right.