I've been using NVidia Geforce Experience to take screenshots in game, but I noticed in the game options some settings for a screenshot tool, such as whether or not to leave the UI in them and what format they should be saved as. I couldn't find any way to activate the built-in screenshot tool or any other references to it being there. Can anybody tell me how it works if it's there?

You can natively take screenshots in PSO2 using the PrtScn key.

The screenshots are saved to "Documents/SEGA/PHANTASYSTARONLINE2_NA/pictures" or "Documents/SEGA/PHANTASYSTARONLINE2_NA_STEAM/pictures", depending on your version.

There isn't any full-blown robust screenshot tool or photo mode, but there are various other built-in options that you can use to enhance your potential screenshots, such as the Fixed Cameras and Custom Lighting options which you can access from the Quick Menu, and various Chat Commands that you can use to make your character make facial expressions or even to freeze Emotes (all of which were slowly added to the game over years).

@AndrlCh Ooh. Thanks. I'll try that later. I didn't know about those chat commands either.