I don't think this belongs on the card to be honest. Otherwide each legislative adjustment would require population-scale updates.

This can go into the reader of anybody who e.g. sells beer to pick your example:

  1. Reader knows beer >= 18 because reader is in Germany  
  
  2. Reader asks card to verify >= 18
  
  3. etc.  
  

Self exclusion would still be possible if there is a standard for it.