It was common to have a headlight levelling dial for a period, I’d say from the 2000s up to mid-late 2010s. Prior to that most cars only had mechanical adjustments, post that most cars have auto levelling headlights - over a certain brightness this is legally required.

You might find a setting for headlight levelling buried in some car settings still but I don’t recall a physical dial for this in cars I’ve driven from the last 5 years or more.

Note that this might be a country specific thing, particularly re. requirements for auto levelling (this is true in Australia at least).

I do like finding signs warning of a particularly specific problem, always makes one wonder who it was who caused the sign to be installed and how they feel about it. You’ll often find that even generic signs like “Don’t let items burn in the toaster” had a root cause in a specific incident (or string thereof).