4th grade questions

So I have a 3rd grader (rising 4th grader) and am pondering the jump in workload that seems to come with 4th grade. He is a great reader, and has been doing independent assigned readings this year, about one per day. We also read aloud history, science, and literature together. He of course reads a ton in the afternoons during his free time from books I get from the library for him. I am curious to hear about what sort of workload people have for their fourth graders. How many readings? How much is done independently? How long do things take? Have you added in Plutarch, Shakespeare, written narrations, grammar, dictation, or Greek/Latin? He is a young 4th grader and will still be 8 when we start our new school year in late July. He isn’t much for writing, though we have been consistent with copywork. I also have 3 younger ones and like to do things together to some degree. Do I need to split off his history readings for higher level content and do the lower (1-3 grade) readings with my youngers?

I am thinking of just doing dictation this year, and possibly adding in one written narration per week by the end of the year. He really enjoys his free time for legos, reading, and playing outside with his sisters. I don’t want to infringe on that more than I have to, especially since I know he is always reading and learning things that I haven’t assigned him as part of schoolwork.