There's a tool, GSM that lets the PS2 output up to 1080p via composite. I haven't found any real game that supported it. I think FFX could output 1080i. You could either force it by running the GSM elf file then running the game or changing the settings in OPL to enable GSM with said resolution. I only use 480p since 480i (usual default) is pretty awful on my TV. It's game dependent like Chaos Legion doesn't even work with 480p but Street Fighter EX3 could run at 720p but it looks super small like 1/2 the screen height. I prefer using the GSM in OPL since the GSM elf kind of fucked my PS2 when I set it to 720p and the PS2 doesn't recover when I reset it. I had to use the composite cable to restore it back to the default setting.