If the Arc is hooked up via HDMI ARC or eARC, then it should be telling the TV’s CEC that it can accept up to Atmos. 

Several things to ask, to better understand the situation.

Which Sony TV?

Is CEC (I think they call it Bravia-Link) turned on?

Are you using the HDMI cable supplied by Sonos to connect the Arc? Which HDMI port on the TV is it connected to?

What is the source of the video? Is it a Dolby Atmos source, or is it just stereo?

Hooked up to the eARC. THE brand of the tv is Bravia. I’m not sure of what CEC is or where to find that?  The arc is being used by the hdmi cable it came with and is in the eARC ON BACk of tv. Not sure Dolby or Stereo. Assuming Dolby but like we were watching the Super Bowl tonight. When I change settings for base it doesn’t change much like my five speaker and or the 100’s. Those speakers can blow people out of the room. This arc, not so much. 

I don’t think you’ve looked far enough. The brand of the TV is Sony, you said so above. Bravia is a line of theirs, but isn’t specific, as to which one you have, we need the model number to help more completely. This is likely printed on the back of the TV, or more easily accessed in the menu on the TV. 

What speakers do you have beyond the Arc? You mention a Sonos Five and a pair of (or more?) Era 100s? How are they set up? Are they showing as surround speakers in the same room as the Arc, or do you have them set up as separate rooms? What device is feeding the TV set the Super Bowl? What are the audio settings on that device?

Bravia-Link (or CEC, until you tell us which model TV you have, we aren’t sure what it is labeled) would be a setting in the audio settings of the TV set. It should be turned on. But, if you’re using a cable box, or Apple TV, or anything else feeding the signal to the TV, CEC needs to be turned on on that device as well, so the CEC computer can tell that device what kind of signal to send.

Just to check, you weren’t using YouTube to watch the Super Bowl, were you? That would add a layer of complication, I suspect. I don’t use YouTube TV myself, I watched it on the local Fox affiliate out of Seattle.

When you’re watching other things, does the Arc sound different, and you only noticed this on one channel or the Super Bowl in particular? Have you called Sonos Support directly to discuss it?

When you speak directly to the phone folks, they have tools at their disposal that will allow them to give you advice specific to your network and Sonos system.