Responding to OP, they're definitely going to begin their plans for mass deportations. Connected business interests will push back, with what success I don't really know. I don't think this is a thing Trump is going to fold on when his rich friends tell him it's bad for business, because ultimately it's something he personally really wants to do and the last people in his ear (the freaks that will staff his administration) really want to do it as well.
The good news is that the entire federal government (excluding the armed forces) doesn't have nearly the personnel to accomplish what they're aiming for. The bad news is they'll just deputize local and state law enforcement, who will be extremely eager to abandon real policework (to the limited extent any of them actually do any) for SS shit. The surveillance and incarceration capabilities that all of this will require will require turning America into something very dystopic (our entire prison population right now is around ~1,200,000), but a lot of us probably won't see most of that shit. What worries me most is when someone shows Trump the cost of all of this and he has a "it doesn't cost $60,000 to bury a fucking Mexican" moment and begins ordering for everyone who gets rounded up to simply be shot. The biggest restraint on that is he won't want people seeing that shit on TV, but he may figure that Elon's control of Twitter will be enough to effectively hide it from the public.
A side effect of all of this is that crime will increase as police spend 100% of their time on deporting immigrants.
He may be dissuaded from instituting the worst of his proposed tariffs, but that's another thing he really wants to do so again I doubt it. We'll see inflation jump and an even steeper rise in housing costs as new construction is undermined by the elimination of its labor force.
As for health and the environment, well we all gotta die sometime right? Food, medicine, and drinking water regulations will be effectively eliminated, when not expressly then by refusal to enforce them. They'll repeal the IRA to halt the green energy revolution and pretend they're coming up with a better alternative, but that alternative will just be giving all of that money to Elon to do whatever he wants with it. I'm less sure they'll repeal the ACA, even though I think they'll have the votes if they decide they want to do so (this assumes the Dems narrow path to still take the House doesn't come to fruition). That was a big promise last time, but I don't think Trump really cares about it personally and there's not a ton of money to be given out there to his billionaire supporters like there is with an alternative to the IRA.
Obviously there will be a whole lot more awful shit that we can't really predict right now.