The PCGamingWiki recommends "ThirteenAG's Widescreen Fix" for modern resolutions, which is typically downloaded as a .zip file and extracted into the game directory. Downloads - Rockstar Games
Search for Grand Theft Auto III or use the package name com.rockstar.gta3 . It is a paid application that requires approximately 1GB of free space. Download com rockstar gta3 zip
You can purchase and download the Grand Theft Auto: The Trilogy – The Definitive Edition directly from Rockstar Games . Download com rockstar gta3 zip
The Definitive Edition is available on Steam and requires a modern 64-bit processor and 8 GB of RAM. Technical Support and Patches Download com rockstar gta3 zip