Hello,
Unfortunately this is the way how it is with ELS. The headlight key is bind with takedown.
Depending on the vehicle model, you may or may not be able to switch between low-beam and high-beam.
For vehicles that don't support takedowns, you may switch between low-beam, high-beam, and off.
For vehicles with takedowns enabled, you may not be able to control highlights the same way as a valina GTA vehicle, or a non-els vehicle.
However, you can try to disable takedowns for a particular vehicle in its .xml config: "<Takedowns AllowUse="false" Mirrored="true" />."