IsEnormous is a script tag found within char.dat. It is only used to immediately state that a character cannot be transparent - this means the player cannot see terrain behind the character if the character is blocking their line of sight. Any further implications are unknown and unimplemented.
An enormous character normally blocks line of sight unlike most entitiesas if it were actually a wall. However, an enormous character ceases to block line of sight if it is either composed of a transparent material (e.g. glass) or is currently invisible.
Current enormous characters: