There is nothing API like that will tell you you are in a red circle. You simply need to use the game's idea: Chaneg the color to somehting more visible in the settings and use your eyes, or learn what bosses and enemies say to the NPC chat before a red circle appears (mechanics).
You can only react on incoming damage, and then it's too late ...
That said most circles and ingame 3d stuff is not accessible via addons or the API. You can add your own textures and markers but what isn't given is information about enemy/player positions movement (except for grouped players -> position).
If there are buffs on your player or the enemy you are able to read you can react on this. But animations of weapons, enemies and so on do not trigger any event or api stuff you would be able to react to. Sometimes there is a chat NPC message, sometimes there isn't.
There are some major warnings if you enable them in the settings like "dodge" or "block" which you are able to use within addons.
what about for incoming damage checks?
Like I have seen the combat parse mod allows you to see things that damage you. Would there be a way
to ask if an attack was for example; ground placed, an Aoe or if it has a duration?
No, you just can get the data from EVENT_EFFECT_CHANGED or EVENT_COMBAT_EVENT and they do not provide any info about aoe or not. There is no api for this afaik. https://wiki.esoui.com/Events#Combat
You coudl just check the buff type or other types that the events provide AND compare abilityIds/buffIds to a list of pre defined ones, like srendar and other addons do.
Much work to keep them updated after changes/additions...