To avoid the "squashed" look of a 4:3 image stretched to 16:9, use your graphics card settings to add black bars:
While there is no official 2021 standalone "fix," the community consistently uses a combination of configuration edits and specific versions to achieve widescreen in Heroes of Might and Magic V Recommended: Use " Tribes of the East heroes 5 widescreen fix 2021
Navigate to: \Documents\My Games\Heroes of Might and Magic V\Profiles\[YourProfileName]\ Open with a text editor. To avoid the "squashed" look of a 4:3