Contents:

The battery is in the trunk under the compartment cover.
When replacing the battery, disconnect the negative (-) cable (1) and remove the positive (+) battery fuse box (2).
Remove the battery mounting bracket (3).
WARNING - Touching metal surfaces in the trunk under the compartment cover

Do not touch metal surfaces in the trunk under the compartment cover while the engine is operating or hot. Doing so could result in serious personal injury. Turn the engine off and wait until it cools down or wear gloves to replace the battery from the luggage room.
Your vehicle has a maintenance-free, calcium-based battery.
When recharging the battery, observe the following precautions:
Reset items
Items should be reset after the battery has been discharged or the battery has been disconnected.
Kia Stinger (CK) 2018-2023 Owner's Manual: Air bag inflation conditions
Front air bags Front air bags are designed to inflate in a frontal collision depending on the intensity, speed or angles of impact of the front collision. Side and/or curtain air bags Side and/or curtain air bags are designed to inflate when an impact is detected by side collision sensors depending on the strength, speed or angles of impact resulting from a side impact collision.Kia Stinger (CK) 2018-2023 Owner's Manual: High Mounted Stop Lamp
Repair procedures Removal 1. Disconnect the negative (-) battery terminal. 2. Remove the tailgate upper trim. (Refer to Body - "Tailgate Trim") 3. Disconnect the high mounted stop lamp connector (A). 4. Remove the high mounted stop lamp (A) after loosening the mounting bolts.