Chrono Trigger is so far ahead of its time, it’s insane. Enemies visible on the field map, battles taking place directly on the field map, character positioning mattering immensely, multi-character attacks, incredible music that holds up today, a compelling story with something like 15 total endings (granted, it’s not like they’re ENTIRELY different from one another, there are a few major branches with a few variations each)… Most of these things would all but vanish from games for twenty-plus years. I remember when Final Fantasy 12 came out, it was lauded for having the enemies shown on the map and battles taking place on the map as well.
You can actually have the game ask for opportunity attacks. If you open your character tab (or party view), up at the top, there’s a tab for “Reactions”. You can set it to automatically take opportunity attacks or ask before.