There’s all the way from 480p to 1080i but in my experience very few games worked forced 480p and when they did there were all kinds of glitches, parts of the screen cut off etc.
PS1 games output their native res on a ps2. Freemcboot doesn’t offer any options for PS1 games although it does make it easy to swap discs to play burned PS1 games.
My preferred option for ps2 on a flatscreen is actually a phat PS3 with BC. It actually does a terrific job deinterlacing and I use component cables into my OSSC to add scanlines.