I should have added this earlier USA Baseball has been doing a series of virtual clinics since everything started shutting down, replays of are available on their youtube channel. A lot of the presenters are college coaches so while they share some really good information it would definitely have to be adapted for a small high school program, but they did have some really impressive (to me at least) high school coaches on some of them. Stick and Ball TV also did some virtual clinics that had some really good information, replays were available as of a couple of weeks ago but I lost the link so Im not sure if they are still available for free.
There is also a lot of coaches that share various things that they do in their program on Twitter. Chuck Box is one in particular that I've seen share some examples of his practice plans/off season plans ( I wanna say it was in April or May) that may give you some ideas about how to structure things. He has also taken part in a couple of the clinics that I mentioned above (sorry don't remember when those were so I can't narrow it down as to which ones to look at).