This refers to faces that are so beautiful, people wish they were designated national treasures.
It’s an expression that is often used by the younger generation to praise idols in the entertainment business.
Similarly, the expressions “national treasure level handsome man” and “national treasure level beauty” are also used.
ni shitai hodo
that are so (people wish they were designated)
no koto wo ii masu.
(this) refers to
(the) younger generation
idols (in the entertainment business)
home tataeru toki ni
(that is) used
national treasure level handsome man
national treasure level beauty
to iu hyougenn