Hi everybody,
I have a u3 project where any character of any size can have an armor of a basic model, that’s why I need to change their look when different armor is on.
Can this issue be solved in unity and how to map the armor to the character model?
Is there any docs about this problem?
Welcome to the forum, Homer J (although I suspect that is not your real name 
Unity’s Character Customisation example (available from the Asset Store) contains code to swap a character’s clothes. A different approach that sometimes works better for armour is to parent the armour pieces to the object’s bones. Essentially, a bone behaves like a child transform in Unity, so you can locate it using transform.Find with the appropriate “pathname” (see the doc page for an example of how to do this).