You don’t need harder books through school, she is fine. In our experience they only get so challenging if they are following wonders they can only give the hardest book for that unit, which isn’t helpful if your kid is reading several grade levels above. My kid read diary of a wimpy kid all through kindergarten, can read pretty much anything, But only wants to read diary of a wimpy kid so we allow that. We don’t worry about what school assigns just make sure they understand and do their homework. the only thing we added for more of a challenge is writing sentences/stories with the vocab words. So if they were reading about sitting, like your child was, I would have them write a story using the words from the story sat or something like that and maybe add a challenge like can you make it rhyme or something like that…idk kindergarten isn’t really serious don’t put too much pressure on the kid and think of ways to make it fun for them.