100% yes of course
"Don't do this at home"
When you PROPERLY shorten the terminals/battery of your alternator the engine will die. Myth busted lolz.
Lights,Break Lights,Aircon,Amplifier,Sound setup. Anything that requires electrical load will affect your RPM. A mechanism or devise such as an Idle Air controller or Idle up in carbs will compensate for those loads thus affecting already your idle.