By default, Apple Books paginates from left to right. However, for some languages like Japanese and Chinese, you might want right to left pagination. Apple Books 3.0 (or later) supports both pagination directions. You can define the pagination direction by including the page-progression-direction on the <spine> element in the OPF. The page-progression-direction attribute is a global attribute and therefore defines the pagination flow of the book as a whole. The allowed values are "ltr" (left-to-right), "rtl" (right-to-left), and "default". If you specify "default" or if you do not specify the attribute, Apple Books can choose the rendering direction.
<spine page-progression-direction="ltr"> <itemref idref="cov"/> <itemref idref="tit"/> <itemref idref="ch1"/> <itemref idref="ch2"/> <itemref idref="end" linear="no"/> <itemref idref="bib"/> <itemref idref="cht" linear="no"/></spine>