The answer
Coptic iconography is unique in that the icon is not intended to be merely viewed but rather to be read. The persons in the icon look like the icon of Christ. Thus, the iconographer creates the image of Christ first, then uses the same features for the saints and angels in the icon. The saints reflect the Lord Jesus Christ in His image, by their lives, faith, and deed.According to the Coptic Orthodox Synaxarion, St. Christopher was martyred in the third century. Please read the following links:
https://st-takla.org/Full-Free-Coptic-Books/Coptic-Synaxarium-or-Synaxarion_English/08-Bermodah/Coptic-Calendar_02-Baramouda.html
http://www.stabanoub-dallas.org/index.php?option=com_content&view=article&id=105:saint-christopher&catid=42:Cop_Saints_cat&Itemid=55
The Roman Catholic Church also commemorates St. Christopher as a martyr. However, the iconography they use weaves some legend with his biography. These depictions are not used in Coptic Orthodox iconography but might be used by other churches.
Answered by His Eminence Metropolitan Youssef (opens in a new tab)