In the original Warcraft on DOS, you would type war.exe and hit enter to play. I found there was another file in the directory. If you loaded war_hack.exe, you could modify units, buildings, gold costs, attack range, production speeds, and more. After editing, you would return to load war.exe with the new parameters. It’s been a while, so this may not be the exact step by step method.... Does anyone know if similar modifications are possible with the GOG version? Thanks!

Yes kt was on Apple Mac + DOS CD re-editions.
As im remember same exe still here and there is still war_edit_readme.txt file explain what war_edit.exe do (warn it is not an map editor but just unit stats editor).
Well. GOG come with full AppleMac audio-included disc image (bin+cue where bin probably renamed to .gog) with all original files of 1.22h re-edition content. Even if DOSBox version GOG installer didnt copy this file you can mount/extract WAR.bin and copy remaining files from there (as i remember there is 0 files need to be copied).
Apple Mac version better quality music did not played in GOG version by default on Windows and MacOSX builds since its only DOS+DosBox+Mac-DosBox.

Mmm... Blizzard did announced war map editor back in 9x? But never released or... did release it? There is a lot of thing lost from that era along with older websites. And Internet Archive for many such official things have even no references saved (eg there was patches for GTA 1 but now only demo-patches are obtained from Internet Archive of gta website; flash-shockwave or C# small mini-games for Shogun TW or Hogs of War).

But as i remember un-official editors was created. Maybe even more than one (unrelated to each other). More time flow less chances to find even mention on the Internet about that,nnither the download link (like SupCom FAF Refugees fork of fan mod+server FAF for SupCom FA).

Warcraft Fandom Wiki or Wowpedia have some info about official and un-official editors for Wc1. Which is 100% sure - both official and un-official tools once existed. War_edit.exe are in game folder. And at least one 3rd party.

As i remember official in-game folder war_edit.exe allow to edit just unit-stats and not even any else (not building and no else modification). What you describe to modify can be in 3rd party tool (or never possible?)

the gog version does come with war edit. you can edit a lot of stuff there.