To connect your TV box to a soundbar that only has a USB-C connection, you can use a USB-C to 3.5 mm jack adapter. Such an adapter allows you to forward the audio output of the TV box to the soundbar via the 3.5 mm jack connection by using the adapter between the TV box and a device with a USB-C connection. However, you need a device with USB-C that supports audio output via the USB-C port, which is not the case with most soundbars. A direct connection between the TV box and the soundbar via a USB-C to 3.5 mm jack adapter is therefore not possible if the soundbar does not have a suitable USB-C connection for audio.

Alternatively, you could consider a Goobay USB adapter audio jack plug if it is suitable for your specific application. However, it is important to check whether the adapter is compatible with your soundbar and whether it supports the required audio function.