In the US, there are beginning reader books (e.g. the “I Can Read!” and “Ready to Read” series) which intentionally use somewhat limited vocabulary. These are s

In the US, there are beginning reader books (e.g. the “I Can Read!” and “Ready to Read” series) which intentionally use somewhat limited vocabulary. These are somewhere between a picture book and a chapter book: they have usually 1.5 pages of text and 0.5 pages of picture in each 2-page spread; the text is set in a large font but there are at least a few sentences per page; usually the books are 30–50 pages long, with 3–5 “chapters”. I don’t know how useful these are for independent reading by 5–6-year-olds, but anecdotally they are great material for reading to 2-year-olds, better than most picture books. (Note: some of the recent readers are garbage marketing gimmicks with movie tie-ins, ranging from boring to incomprehensible; skip those.)