Benz MBUX 2021 YO
This theme was introduced in updates Ksw-Q-Userdebug_OS_v4.3.3-ota, Ksw-T-M600_OS_v1.3.8-ota and Ksw-T-M700_OS_v1.1.5-ota, therefore it might not be available to activate on earlier firmwares.
To make this theme available for selection in your factory settings, you might need to modify your factory_config.xml file. Find the <SupportUIList /> section and add the following line: <Item id="1" name="UI_MBUX_YO" display="Benz MBUX 2021 YO" />. More information and examples can be found in factory settings section.