CA released a set of documents which mention the data structures passed to the various triggers (link in this thread)

https://forums.totalwar.org/vb/showt...ocudemon-files

with entries like

---------------------------------------------------
Identifier: PreBattle
Event: When a battle is about to start
Exports: nc_character_record, character_record, faction, region_id, character_type
Class: ET_PRE_BATTLE
Author: Lee
---------------------------------------------------
data structures like "character_record" are passed to the triggers which probably contains age and some of the data passed is accessible inside the trigger but i don't think anyone ever figured out how to access age (if it's possible - which it might not be).

reading through the files can give you a good idea of what would potentially be possible but either not all the internal data is accessible or no one has figured out how yet (and a lot of people tried).