I'm planning to have a schedule that vaguely imitates the school day - so some literacy and numeracy in the morning, a break, then alternate things like history, science, music, art in the afternoons. Science might be making slime, music might be something like giving them chopsticks and telling them to find 10 things they can drum to make different noises, art will be something craft related. All pretty simple and basic, but a range of activities to mix up things over the week.
Also going to have activities like baking and learning skills (e.g. trying laces).
Going to have projects on the go as well, probably one a week. Something like plan and design a new town, or design your ideal bedroom (they will have to look up and price furniture, paint etc, all on a budget), or plan what you would include in a training programme for space travellers going to settle a new planet.
Some independent play as well - someone posted the 30 day Lego challenge which will keep my eldest occupied!
Some screen time as well - going to try to get some educational programmes, but they'll be allowed a bit of downtime watching their own programmes for a while also.
The key thing for us will be having a schedule so the kids know what to expect and we don't spend all day in pyjamas watching Netflix