Rust is complex. It's solving complex problems. It's not complicated, though. There's not much you could remove without creating leaky abstractions.
In my opinion, C++ is equally complex. It's solving the same kinds of problems as Rust (although it'd be fairer to say "Rust is solving the same problems as C++"). However, it's hella complicated. There's a vast number of twists and turns to keep in mind if you want to use it, and most of them are things you could not have anticipated by reasoning about it from first principles.
If you took the design goals of Rust, and reinvented it from scratch, it'd probably end up looking a lot like Rust. If you were to reinvent C++ from scratch, I bet it wouldn't remotely resemble modern C++. If anything, I bet it would also end up looking like Rust, and the fractal of powerful footguns would be left on the cutting room floor because "that's insane, there's no way anyone would want that".
Gauging how "complicated" a language is somewhat subjective, so it's kind of hard for me to give a straightforward answer. I think it's certainly easier to be (some definition of) productive with C++ than with Rust. I feel like to do anything even remotely non-trivial with Rust, you kind of have to understand everything, because if you don't do it in the "Rust way", it often won't compile. I think this is a good thing, but it does make it harder to get started.
C++ has a lot less consistency and (kind of) more features, and lots of strange semantics to go with those features, and so if people actually use them it can get confusing and hard to read pretty quickly.
My knowledge is a bit out of date, to be clear; previously whenever I need something in the C++ domain, I could fairly easily just reach for C and use that instead. Now Rust is available and I think overall better (though I do sometimes miss how utterly simple and dumb C is).
I confess I haven't dug into it much yet, but this reminds me of how Haskell was. By the time you got a program to compile your project was more or less done.
With Rust, I had to get used to single ownership or explicit cloning. There's an argument that this is "better", but I found it a bit harder to learn.
To be fair, the alternative to having to worry about Send/Sync/Pin is not "not worrying about Send/Sync/Pin". It's having to worry about correctly enforcing the constraints they describe on your own, without any kind of mechanical help. E.g., not moving data to another thread that shouldn't be and not accessing data from multiple threads that shouldn't be. This stuff is intrinsic.
In this sense the Rust mental model is simpler, because failing to uphold these constraints is no longer "your fault", it's Rust's fault.
And relying on people to check them. Versus a compiler.
You can make an argument that the K&R C "is" an utterly simple and dumb language, but if it was it's long gone and it's also irrelevant for modern hardware.
Today because C only has a single kind of reference, the raw pointer, that means if you want references at all (which you do) you need pointers, and to get decent performance from this sort of language you need pointer provenance, and so now all your reference types involve understanding compiler internals minutiae. Bad luck though, those aren't specified in the C language standard, that's a TODO item from the turn of the century. The committee agrees that C pointers do have provenance but declines to explain how that could possibly work.
I haven't seen places where they wanted this, but they definitely can exist. In the cases I'm thinking of any valid pointers are definitely unique (so no aliasing), or they're definitely pointing at something immutable (so aliasing is fine) or both and so there's no problem as I understand it.
There is an outstanding issue with LLVM - for any language including Rust - that it has unsound optimizations for pointers and this has implications for provenance tricks, but as I said that's not Rust specific and I think worse there are signs the same illness afflicts the GCC backend so maybe it's worse than "LLVM is buggy" and is a wider problem in how compiler developers have thought about this vague unspecified problem.