I need an additional chime module also.  TP-Link's website and FAQ's indicate that an additional chime module can be added.   However, TP-Link does not sell separate chime modules - thus, depriving themselves of additional sales and profits!   

On a similar note. I saw that the TAPO hub comes with a built-in chime.   Likewise, I have read that TAPO devices are compatible with Kasa devices, so I purchased a TAPO hub so I could get an extra chime for my Kasa camera.  THAT WAS A MISTAKE AND A TOTAL WASTE OF MONEY, as (contrary to what TP-Link has written their Tapo hubs are not FULLY compatible with Kasa devices.

TP-Link, if you are listening, please make the chime modules available for your Kasa KD-110 Doorbell Cameras!  You'll sell a lot of them.    Likewise, you need to clarify that your Tapo hubs are NOT completely compatible with Kasa products.

Currently, Kasa does not offer a standalone plug-in chime for their wired doorbell cameras. You can explore third-party smart chimes compatible with the Kasa ecosystem or consider using a smart speaker (like Google Nest or Amazon Echo) if your doorbell integrates with them for chime functionality.
e.g: b9game