It may be a subtle correction, but the truth is that God did not “create” himself again. He was “begotten.” He remained one Being, present in three Persons (Father, Son, Holy Spirit). His reason for becoming Man wasn’t to understand temptation, but to take our punishment on the cross.
I don’t understand all this very fully, but this is orthodox.
Jesus did not know it was to take our sin until he understood the temptation.