in Wall Cable Management Kit, Cord Hider for Wall Mounted TV & Soundbar - Includes Power & Low Voltage Cable Management and Circle Saw Drilling Attachment & Drywall Hand Saw

You could use a kit like this and just install the soundbar power outlet. https://a.co/d/07X25LbP Plug into the power outlet behind the TV, and you can run the HDMI audio cable through there, too