Your Mevo comes with headlights which can intelligently sense changes in brightness around the vehicle. When set to AUTO the lights will power on and off as required (including through tunnels).
To check that the headlights are set to auto, look for the dial to the below and to the right of the steering wheel, just a little above knee height.
We recommend you leave the lights on their Auto setting. However, if you wish to change this you can turn the dial to set the lights to your desired brightness.
Additionally, when driving at night, pushing the indicator selector (on the left hand side of the steering wheel) toward the dashboard will activate the high beam lights for additional brightness.
Remember that it is dangerous to drive with the high beams enabled while there are other road users ahead of you (either in your lane or oncoming). The high beam lights on the e-tron are very bright.