Comparing 'upright-ness' across several endurance road bikes

Bike Insights has used stack to reach ratio to compare a number of brands of bikes. One limitation is that they may not have every model and every year of bike entered on their site, but their data appear reasonably complete for major brands. The link I inserted may take you to a comparison of the 2020 Roubaix Comp and the 2020 Trek Domane aluminum (but the carbon Domane has the same geometry). It should show a picture of two overlaid simplified geometry diagrams.

They rate the Specialized in your size as being about average in terms of stack to reach compared to other endurance road bikes, and the Domane as being relatively upright. They discuss their rationale and some limitations of stack to reach here. They do let you visualize how the frame geometry affects the relative riding position between two bikes, although they do not include the effect of the stem and handlebars.

It is important to remember that frame stack is measured to a point just above the head tube (except for the Roubaix, see comments on Adam's answer), and that we further modify fit by spacers under the stem, the stem length and angle, and the handlebar reach. Riser handlebars are rare on road bikes, but a number of Roubaix models are equipped with such bars. Riser bars add further stack to your final position. You may be able to achieve your preferred riding position on any of the models you listed.

You asked about head tube length. To a great extent, the effect of head tube length is already captured in the frame stack measurement. You mostly don't need to worry about the head tube length per se. In the case of the Roubaix, as we discussed, the stated head tube length is deceptively short because it doesn't account for the suspension system (which is mounted in the head tube). The Roubaix's stack measure appears to be taken to a virtual point above the head tube, because the suspension needs some clear space above the head tube itself.