An edition in a language written right to left (Arabic, Hebrew, Persian, Urdu, Yiddish, Pashto, Sindhi, Uyghur or Dhivehi) is built as an ebook that reads right to left: its lines start at the right, its pages turn from right to left, and the contents, notes, lists and poems sit on the right-hand side. Its navigation and the pages the studio writes (Contents, Notes, the chapter names a new manuscript starts with, and the copyright page) are in Arabic, Hebrew or Persian.
Words in another direction. Mark a passage's language in the editor (an English name, a line of French) and the reader keeps it apart, so its letters and punctuation stay in their order. Text you write or paste keeps its own joining and direction marks.
Covers. The cover editor sets a Hebrew or Arabic title and name right to left, in a face with their letters (Frank Ruhl Libre for Hebrew, Noto Naskh Arabic for the Arabic script), and never spaces Arabic letters apart.
Looks. The classic and modern looks are ready for right-to-left ebooks. The elegant look isn't offered: its drop caps would split joined letters, and the Arabic script has no italics. Arabic-script editions are never letter spaced.
Print. Hebrew and Yiddish editions print too: set right to left in Frank Ruhl Libre, a Hebrew book face, bound on the right, with the cover wrap and KDP's reading direction to match. They print as paperbacks and large-print books; KDP makes its hardcovers in Hebrew and Yiddish only left to right, so they have none. KDP sells Arabic and Persian books as ebooks only, so those editions are ebooks, and it sells no Yiddish ebooks: the studio still makes the Yiddish ebook, for the stores that sell one (the where-to-sell guide shows which). IngramSpark's files for books read right to left are still to come.
Ebooks written right to left come with the Author plan, or a Book Pass for the book.