No, the word "maknae" is not a choreography line in K-pop.
The term "maknae" is derived from the Korean word "maknaejeon" which means "youngest child" and is commonly used by K-pop fans to refer to the youngest member in an idol group. Even though the term isn't used in songs or dances, maknaes often find a special place in fans' hearts as they often provide comic relief or show off their natural talent in entertainment shows.
Apart from being a fan term to refer to the youngest member in an idol group, "Maknae" can also refer to a specific type of dance or stage performances done by the youngest member of the group. Usually, the performance involves showing off the member's unique talent or skill which helps them stand out from their group members. For example, Taemin of SHINee debuted as the youngest member of the group and he's known for his flashy solo choreography which goes beyond what the other members are capable of.
Overall, "maknae" is a Korean fan term used to refer to the youngest member of an idol group. It does not refer to a specific dance or performance line but can refer to the special stage performances and routines of the maknae members.
