This video compares the three anti-aliasing settings available for Marathon on the PlayStation 5 Pro: PSSR, CMAA and FSR.
You can find the comparison below:
At a glance, CMAA appears to be the sharpest, followed by PSSR and then FSR. However, it is really hard to differentiate between the three, especially in motion. The game was able to maintain a perfect 60 frames per second with all three anti-aliasing settings.