Performance and FOV settings are usually managed via GAME.INI and VIDEOOPTIONS.INI located in your Documents folder.
If you are using this file to dive into the game for the first time, expect an extremely ambitious (if unpolished) experience: File: XENUS.II.WHITE.GOLD.zip ...
Modern players often need to perform manual tweaks to ensure the contents of the ZIP file work correctly: Performance and FOV settings are usually managed via GAME