It depends on the battery chemistry but the Ioniq 6 is Li-ion I think that likes to be in the ‘Goldilocks zone’ for optimal long life. However, most modern EVs have top and bottom buffers so that the pack is never really full or empty.
DC charging beyond 80% is rarely worth the time taken to charge the last 20%, but the reality is the battery will probably outlast the car and you can just let the battery management system look after the battery.
Personally, I charge the car to 80% unless I know I’m going on a long journey when I charge to 100% before setting off.