While medical info is available to responders arriving at the victim and is well worth setting up, Apple Watch does not include a means to add additional info to text or to speak to the dispatch center.
Check with the local fire department, as responders can use a “Knox box” or other means of gaining non-destructive entry in an emergency. Most fire departments with sufficient commercial establishments, multiple-occupancy apartment or condo buildings, or similar, will have some sort of non-destructive entry program.
Alternatively, acquire and save the direct (non-911) number for the dispatch center where your parent resides, set yourself up as an emergency contact in your parent’s iPhone, and you can call the dispatch center with the necessary info on the non-emergency (“direct”) number.
But… With varying degrees of damage… Gaining access to most buildings is pretty easy, to be blunt.