Most Children's book (suitable for kids up to the age of five), come usually in a 32 pages format*.
Cover and back cover.
12 double-page spreads are available for the story, text/images (24 pages total).
Two pages are glued to the Cover/Back Cover.
One left-hand page spreads + One right-hand page spreads (4 pages).
(These four pages could be, of course, part of your narrative)
One page for technical information, copyright, numbers of copies, dedications, etc.)
One page for the Title.
NB: This pattern corresponds to a standard book with hard cardboard covers.
Of course, there are other standards.* Dictated by the way books arefolded and bound in multiples of 8 and/or 16 pages.