That's correct Ellie, they will come on dimly with the side lights known as dim-dip.
If you drive up to a wall with the sidelights (or no lights) on and the engine running, your sidelights should be on as day running lights ("Guiding Lights" they call them in Sweden) and the headlights on dim-dip and then use your smartphone video camera, the lights will appear to flicker on and off - we can't see this normally but it's the same principle as the wagon wheels going backwards on a forward traveling stagecoach in an old Western film. It's all down to the frames per second.
Switch the headlights on and they should steady out and get brighter.