No it's not. They just like slavery. If it was about states rights they wouldn't support sending in the military.
What I find shocking about comments like yours is the reminder that propaganda works. Someone in the republican party decided "guys, advocating for slavery openly doesn't go over well, let's tell them it's actually about states rights", and loads of people actually believed it.
I'm not in support of administration or MAGA.
But, to be pedantic, you can be for states' rights, but against states overstepping Federal powers.
Immigration is, currently, a Federal power.
Who is and is not a citizen is not a state's decision.
Just because you're in favor of state's rights (I am), does not mean you think every single issue should be a state's issue.
Maybe you'd like each state to fund their own SS and Medicare. But that's not how it is. And it's unlikely to ever happen.
It was the Democratic party that historically supported slavery and opposed the civil rights movement. The "states rights" euphemism was invented by the Democratic party not the Republican party.