Just installed the GOG version on Windows 10 (21H2) and the game has some weird issues.

To fix them all it needed was the "ddraw.dll" file from DDrawCompat.
Version "DDrawCompat-v0.6.0.zip" works a treat for me:
https://github.com/narzoul/DDrawCompat/releases

Not only does it fix the startup issues but the game looks much better, here's a comparison:
GOG wrapper default screen fit setting - https://i.imgur.com/TjXXZeA.jpeg
DDrawCompat v0.6.0 wrapper default setting - https://i.imgur.com/9vGsVCo.png
Screenshots above are from a 4K monitor (3840x2160)

TBH, the main difference I noticed is that the second picture has an incorrect aspect ratio...

But one advice I have for you is that you should go to the FONTS folder in your Warlords 3 installation, and double-click the files there to install them.

Oops, I had the links pointing to the wrong images, fixed. Never noticed that, thank you for the tip!