I would like to recommend Córdoba or Picado for your child. About the guitar's size, you have to bring your child to guitar store/shop to have a look and try...or have an experienced guitar teacher first. S/he will give you better suggestion based on your child's hand size...to keep your child's interest to learn guitar, first nice sound, second easy to play...that means always use smaller guitar.
2014 Otto Vowinkel Concert 650, Cedar/Brazilian Rosewood
2015 Juan Hernandez Torres 640, Spruce/Indian Rosewood
2016 German V. Rubio Concert 635, Spruce/Flamed Maple
2015 Kenny Hill Performance 630, Double Top(Spruce/Cedar)/Flamed Maple