Kia/Hyundai EVs suck with 12v management, not all EVs. I can park my Tesla for 6 months and it will fire up just fine.
The 12V needs to be charged to 100% on a dedicated battery charger occasionally for optimum life. The car will never do that by itself. And if the battery has died, that’s the only way to get it back to a reliable running state. (Though it’s probably damaged if it went below 10v for any extended period of time)