https://www.mmo-champion.com/threads/851583-4.0-Maximum-Graphic-Settings
The following macros will help you crank up the graphics settings to the very maximum, or to the very minimum (beyond that which can be configured in the video options GUI in-game).
Simply copy these blocks of commands into new macros, drag them to your action bar, and run them. You may need to restart your game client for the changes to fully take effect.
Enjoy!
Maximum Improved Graphics
/console farclip 1600
/console horizonFarclipScale 6
/console skycloudlod 3
/console waterDetail 3
/console reflectionMode 3
/console rippleDetail 2
/console shadowmode 3
/console shadowtexturesize 2048
/console particleDensity 100
/console environmentDetail 150
/console groundEffectDensity 256
/console groundEffectDist 600
/console groundEffectFade 1277
/console spellEffectLevel 200
/console ffxGlow 1
/console ffxspecial 1
/console ffxnetherworld 1
/console ffxDeath 1
/console sunshafts 2
/console textureFilteringMode 5
/console componentTextureLevel 0
/console terrainMipLevel 0
/console ssao 2
/console ssaoblur 2
/console weatherDensity 3
/console gxmultiesample 8
/console violencelevel 5
Minimum Reduced Graphics
/console ffxGlow 0
/console ffxspecial 0
/console ffxnetherworld 0
/console ffxDeath 0
/console spelleffectlevel 3