I have a oxygen converter that requires a 20 amp 12 volt power outlet. I’m looking for a 2008 mini van.
They all have one. Some have two.
But, 20 amps is pushing the capacity of the circuit. Double check what those circuit ratings are.
You could always go to an auto electric shop and have them install an outlet for you. Better yet, consult them before hand if you are going to be using this constantly. That way you can be sure that the charging system on you candidate vehicle is up to snuff. 20 amps is quite a bit to add as a constant load. Guys, what is the rating of most minivan alternators, 100-150 amps maybe. That would be 15-20%. That might be fine if the vehicle is driven a lot between starts. If it is used for short trips, maybe not.
OTOH, if this converter calls for a 20 amp outlet, it probably only draws 15 continuously.
To answer your question, most cigarette lighter receptacles are rated for 20 amps. But that’s the upper limit. You might want to have a dedicated outlet installed for your device. A standard alternator will do fine, except maybe at night with headlights, heater and wipers all operating too. Heavy duty alternators are usually an option on most cars…