Actually not. As Philip Bump explains in this WaPo column, Kamala actually has a bigger lead with RFK out of the race than with him in it. The difference is small (1 point) but it’s hardly a given that RFK dropping out (as is now expected) will change much at all.

I'm not sure that Bump's analysis tells us anything meaningful. Comparing the head-to-heads with the multi-candidate race is certainly going to be within margins of errors of those two questions, of course; but it ignores two major real world differences. The first is that RFK would endorse Trump, which is different than him simply not being available as a choice. The second is that state-by-state races matter far more than the national one.

So if least some of RFK's supporters are actually supporters, then some of the folks that might vote Harris (or just stay home) if RFK just dropped out might end up moving to Trump if RFK partners up with Trump. That RFK can help Trump with his endorsement, not just his absence. Plus, RFK might bring his funding source (Nicole Shanahan) with him.

And Harris polls slightly better in the multi-way in swing states than the head-to-head. Which I wouldn't make much of, since the margins of error are even bigger in the state polls than the national - but still, if you're guessing which way the slight benefit runs, I'd say Trump:

newsweek.com - How rfk jr dropping out would affect trump harris battleground states