LesTyebe: Upon installation, game ran in its base resolution. Tried to adjust in menu. Only crashed upon restart. Uninstalled. Found the configuration page on PCGamingWiki. Look for the Widescreen Resolution section. Re-installed game and followed page directions. Now runs in 1080.

The downside of this method is a hex editor program (I used HxD) and some basic knowledge of its use are needed. While it might seem complicated, it's really just replacing some numbers (which ones and where are explained on the linked page) in the .cfg file. If you already have a back-up or the game installer, the worst outcome would be re-installing the game.

Disclaimers: While this worked for me, there is no guarantee. And, if you don't quite trust the advice of a random internet stranger, maybe that's for the best.

More edit. After more testing, the .cfg file seems to be reset to original by the game, so it can be re-edited, or use Notepad++ or similar to change the .cfg file to Read Only.

smuggly: After reading the Hex how to I'm confused Which line do I alter in the CFG file and where do I put it. I need a 1080p result?

LesTyebe: Attempted clarification.

1. Find the graphic.cfg file in the main Ascension to the Throne game folder.
2. Open graphic.cfg with HxD or other hex editor program.
3. First lines in HxD editor look like:

Offset (h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F Decoded text
00000000 80 07 00 00 38 04 00 00 16 00 00 00 00 00 00 00

The "offset 00" and "04" in line #4 of the PCGamingWiki instructions means the numbers in the columns directly below "00" and "04" displayed in the first line of the HxD editor. Replace the numbers directly below "00" and "01" with "80" and "07"; then replace numbers directly below "04" and "05" with "38" and "04".

Perhaps didn't make clear enough the requirement of using HxD or other hex editor program in original post.

Included screenshots of source page and HxD open together showing which to change, and HxD open with original and edited graphic.cfg files displayed.

smuggly: Thank you very much for this it helped a lot.
One small thing when using this. The Exit game tab in menu is not clickable. Strange.

LesTyebe: You are welcome.

About the menu, hover mouse on selection menu starting at "New". Move slowly down. Notice the second highlight light activates between "New" and "Load". The third highlight activates between "Load" and "Options", while the forth is now on "Options" and fifth on "Credits". So clicking on (from bottom) "Credits" activates "Exit" function, "Options" = "Credits", the space between "Load" and "Options" = "Options", space between "New" and "Load" = "Load" while "New" is still "New".

All in-game menus appear to be proportional, so a trade of slightly more cumbersome main menu for better gameplay resolution.