On the store page it does not say a release date so I'm not sure it is HD or not!

These games were published approx. 30 years ago, between 1992 and 1996.

Based on this information, I believe that you will be able to make an educated guess.:-)

Like many OLD games on Gog they are sometimes altered... To run better Or has unofficial patches.

Like even more old games, no changes were made to them over the course of last 30 years.

These are niche games intended for niche audience and as a matter of fact, later games are arguably worse than the first one (while GNB2 and GNB3 are somewhat OK, all things considered, this applies quite a lot to GNB4 and especially to GNB5, which even today contains gross errors), despite having better graphics.

So take it, as it is - these games are approx. 30 years old MCGA (1st one) and SVGA (rest of them) games. And that's it.
(you can try to fiddle with Dosbox, if you want to)