If you have the light switch in the auto position - the headlights will come on automatically at dusk or when you drive into a dark tunnel.
If the car is fitted with HID lights - they have an auto-levelling feature to ensure that when you have a heavy load in the boot (trunk) which lowers the rear suspension - the headlights automatically adjust to avoid dazzling other drivers.
I imagine you can check whether this is working by parking the car facing a white wall with the headlights on and boot empty. Note where the top of the beam shines. Now get a few obese friends to clamber into the boot (which will lower the rear suspension) and check that the top of the beam has stayed in position.