new tv

https://support.sonos.com/en-gb/article/control-sonos-home-theater-with-your-tv-remote

Also...why do you have a new remote? Is it used with a cable box or is it a 3rd party programable remote?

My suggestion if a cable remote or 3rd party programmable remote is to train it to mimic your TV first.  Then follow the instructions in the link.

Most Sonos soundbars, at least the ‘newer’ ones, work via HDMI-ARC, which means the remote doesn’t connect at all to the Sonos device, only the TV set. It’s the TV set’s responsibility, via CEC-ARC, to send volume commands to the Sonos. 

So it may be more germane to ask which Sonos soundbar do you have, as well as the question above. 

Your forum handle suggests a PLAYBAR, which does suggest an IR connection to the Sonos soundbar, but many newer remotes tend to connect, when they can, to a TV via RF. So you’d need to change the remote to IR connection (see the remote’s manual) and then pair it via the link above…although if you set it to IR anyway, to work with the TV, it may just start working with the Sonos as well, since the PLAYBAR responds to IR commands that are normally sent to the TV.