Y'all realize there are three branches of US government right?
Trump commands only one. And he isn't an actual monarch or dictator. He won't be allowed to over step too much.
Either he's going to be rained in or section four of the 25th amendment will be instituted.
There are currently no laws indicating how many work days should be in the 7 day week.
There is no reason to implement such a thing either to take work days away or add them. Work days are dictated by the employer in accordance with how much work needs to be done.
How much someone should work should be negotiated between employee and employer. I understand that this isn't really how it works in the real world but this is how it is on paper.
I bring this up because there's no real way to institute a nationwide "7 day work week" making this question totally pointless and nonsensical.