Mine just turns on and off.
I wanted something more, plus I like to experiment, so I've tried several lights.
My first experiment was this light. I have it on my helmet. It's pretty good. The only drawback is it doesn't have great battery life, and I have to take it off the helmet to charge it, so I only use it for dusk and night-time riding.
This light was originally placed on the seat tube, but it wasn't visible enough there, so I zip-tied it onto the back of the rack, just above the stock light (which I still use.) I like that it blinks brightly, has a couple of different modes, and some day I may try out the laser lights too.
This magnetic induction light is my newest experiment. No battery, no on-off switch. Every time the magnet on the spoke spins past the light it creates an electrical current and flashes brightly enough to be seen in daylight. I don't have to remember to use it or to turn it off again. So far so good; been running it for a week.
I've tried a couple of other lights that I didn't like and gave to the grandkids.