There are books specially designed for different levels. Such as books with phonetic annotation，or book using only "easy Chinese characters" with pictures would

There are books specially designed for different levels. Such as books with phonetic annotation，or book using only "easy Chinese characters" with pictures would be pretty easy to read by very young kids. As for Adult books, I belive a primary school student at about grade 3 maybe "can read" with a little struggle. As they have learned enough basic word to understand the sentences, even if there are few "hard word" remain unknown.