The “secret” to getting a spark is a coil/inductor to create a high voltage and a spark across a gap. Inductors “resist changes in current”.
When you apply voltage to an inductor (relatively) low current flows for a short period of time while the electromagnetic field builds-up, then the current becomes constant.
If you suddenly break the circuit, the electromagnetic field collapses and high voltage is generated as it tries to maintain current through an infinite resistance.
I don’t have a feel for what inductance you need, but you MIGHT need something “big” like [u]this[/u].
Some people take apart the flash from a disposable camera. (The strobe uses a couple-hundred volts.) But, can you still find disposable cameras?
A couple of things about a “basic circuit” like this - You’ll waste lots of current& power if you leave the coil connected to DC for too long. And, if you use a switch or relay you’ll get an arc across the switch contacts (maybe across the switch instead of across your spark-gap) and this will quickly deteriorate the switch. In a car, the spark-coil is actually a transformer and the contacts (or electronic ignition) operate on the lower-voltage side so the spark goes to the spark plug.
Professional fireworks use disposable [u]igniters[/u].
Or, you might try a [u]piezo igniter[/u] which are used for model rockets or gas BBQs.