Not really. SP and other cheaper/heavier sets will normally take a smaller post, but can be reamed to 27.2, so the post size doesn't prove it's not heavier stuff. But reaming is work, so for efficiency (laziness, cheapness) it's rarely if ever done on production bikes. You can't rule out mods done by a previous owner though.

If you take the bottom bracket bearing out and look inside the tubes there, look to see if there are raised ridges in a slow spiral, like helical splines. That would indicate something like SLX, SPX or TSX. If those tubes are all smooth bore, then you've eliminated those 3 with the X in their name but it still leaves a lot of possibilities.

My advice is don't worry about it, ride and be happy. Unless you're trying to flip it for profit and want the magic words to help sell it, the model of tubing used won't affect your own enjoyment.