Identically to all other American presidencies, which is to say the slow and steady decline of neoliberal capitalism into fascism. How RFK would flavor his portion of that decline is really what we're talking about here and it's honestly irrelevant.
Rad AF, as in Radical liberalism with American First values.
Idk, actually, probably the same as usual with the crank-ism wrenches up to 11?
Similar to Biden, except with zero investment in vaccines because he's a fucking idiot.
Neither party would be particularly interested in working with him, very little would get done
Other than conspiracy shit he's not particularly radical in any of his personal beliefs, the left of Biden on some issues, to the right on others, but I haven't seen any issues where he is as left as Bernie is besides some foreign policy beliefs, which is also a mixed bag
He's basically an economic sort of radlib mixed with reactionary beliefs and an inconsistent view of US empire
I think his most revealing stance is that he believes pharma companies are evil and poisoning the nation (true), but he doesn't believe in a publicly run drug company and his only solution is to regulate lobbying better. Radlib
He's a crank, which means his politics reflect whatever messaging he receives the most. So whichever group of advisors he surrounded himself with would be the direction it would go. This would likely be the same kind of right-wing nutjobs that Trump had in his cabinet.
Probably not much different than recent admins. Trump passed a tax bill and what else? If the country were somehow at a place where RFK Jr got in, it might follow that some reigning in of medical product manufacturers could happen. To me, his ascendancy would signal a degree of public mistrust requiring some modicum of legislation/regulation follow.
Otherwise I don't believe anything meaningful would change in terms of foreign policy or labour power.
(Hopefully regardless of where you are on the vax stuff, most should be able to agree that the existing medical products for COVID aren't good and to me were clearly just the quickest neoliberal fix that could be summoned after everyone abdicated responsibility for managing it. They're bludgeons to get people back to work which also satisfy the criteria that billions of public dollars be laundered to the ruling class via shareholding.)