When choosing a soundbar, consider what you may want to plug into it and which connections you will need. It will likely be HDMI inputs you are most interested in, as these are what you will need these for any 4K Blu-ray player, 4K games console or 4K set-top-box. Many soundbars include additional passthrough HDMI ports, which can be handy to supplement those on your TV and for neat and tidy cable runs. But be sure to check the specifications of the ports for HDR and hfr support, especially if you have a next-gen gaming console.
Alternatively, you might want to plug everything into your 4K TV and feed the sound out to your soundbar via HDMI ARC/eARC, or an optical digital connection.