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: Starter Relay
Repair procedures Inspection 1. Turn ignition switch OFF and disconnect the battery negative (-) terminal. 2. Remove the fuse box cover (A). 3. Remove the starter relay (A). 4. Check for continuity between the terminals (30 and 87) using an ohmmeter.Kia Stinger (CK) 2018-2023 Owner's Manual: Catalytic Converter
Description and operation Description The catalytic converter of the gasoline engine is a three way catalyst. It oxidizes carbon monoxide and hydrocarbons (HC), and separates oxygen from the oxides of nitrogen (NOx). Catalytic Converter (WCC) Repair procedures Removal 1. Remove the engine cover.