Depends on what you consider upgraded. Just off the top of my head the Trail Boss has the same interior as the bottom trim WT, black plastic grill, bumpers, door handles, and halogen lights all around where as the Z71 has a lot nicer interior, painted grill, bumpers, door handles, and LED lighting all around. As far as I can tell the only thing the Trail Boss has over the Z71 is that its 1 inch taller and has the extended a-arms for a wider stance, everything else is way nicer on the Z71.Source? I've seen multiple that it's an upgraded trim from Z71.
https://www.jalopnik.com/the-2023-chevy-colorado-trail-boss-is-the-goldilocks-of-1849345814/amp
GM even lists the models on their website in this order
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