When a dad has a kid and names it a junior do they legally add the Senior to their name? /u/IDidIt_Twice No such thing as stupid questions

A dad, John Doe Smith’s wife gives birth to a son that they name John Doe Smith Junior. Does the dad just get to call himself a senior and write senior on stuff without legally changing his name to senior?

USA.

A dad, John Doe Smith’s wife gives birth to a son that they name John Doe Smith Junior. Does the dad just get to call himself a senior and write senior on stuff without legally changing his name to senior?

USA.