Speaking for USA and NFHS/high school...neither have any rule changes for 2021. Since last season was wiped out, as were the usual national conventions and rule committee meetings, they have both announced that there will be no new rules this year.
NFHS isn’t even printing a rule book for 2021. We’ve been instructed to use the 2020 book for the upcoming season- if there even is a season. I’d like to remain optimistic that there will be. But if you look at where we are now with the pandemic, will we really be that much better off eight weeks from now, when the season is scheduled to start?