As thanks to all the replies.
I have ridden 5 other road bikes with identical dimensions of ETT of 56 with a 10cm stem. I test rode this bike, reach and bike seemed fine and comfortable. The seat is too high is all. The next size down is an ETT of 54, which I am reasonably sure would be too small. I am 5’10, but long torso, short legs, thus I went to 56 ETT bikes a long time ago, this would be my 5th, thus reasonably sure of this size. Trek ships with the larger seat post, they can provide a shorter seat post, if the customer desires to pay $160 (stupid ******g idea) The post can not be trimmed, the design doesn’t allow for that. I could in theory trim the carbon mast which sticks about 4” above the TT junction, but that would certainly void a warranty, nit going there and the price on this bike is very good. The shop indicated I could source a shorter post on E-bay and save about $50 or so. Not sure the history on a used post, begs the question of why as no Treks in this line and Madones ships with smaller 135 posts, they all come with 175, thus wondering how and why a shorter post is for sale used. Part of my dilemma is it’s a great looking bike with a great discount thus am tempted to just cough up the $160 as I am saving a lot more on the discount and if I just pay for the post it’s also under warranty. Thing with seatposts is you set it and leave it. I take it out once a year to clean and re-lube.