I once looked into something like this -- a UNIVERSAL, 100% death tax. When I googled it, it appeared that it could almost, but not quite, replace the federal income tax if you should solve for the fraud and loophole issues. (Which, I don't think you can btw.)
Then you think about, what happens when parents die in a car wreck to the kids? So maybe what you implement is some type of National Life Insurance federal program, geared towards minors or maybe more broadly across the population. Tweaks to Social Security survivor benefits, essentially.
There are also weird questions like, what happens to a company that's singularly owned by the newly deceased? It's sold to the highest bidder, even if it's company run by the whole family?
I don't actually favor this policy for the obvious reasons people will list. But I think it's an interesting question that gets to what it means to have something closer to equality of opportunity.