In the same file, locate filterMode = 3 and change it to 4 . You can further enhance this by forcing 16x AF through your GPU's control panel (NVIDIA/AMD).
Most of these "extra quality" tweaks require editing the Game.cfg file found in the /Program Files/Singles2/Config/ directory. It is highly recommended to before making any changes. Singles 2: Triple Trouble - PCGamingWiki PCGW singles 2 triple trouble mods extra quality