Out of those, Box is the only one that is, and the way that it is is not syntax: it has one exception, and that’s that you can move the contents out of it via a dereference. That’s making existing syntax semantically valid, not introducing new syntax.
In terms of syntax, you create a box with Box::new just like you might any other struct.
EDIT: anyway I'm not saying that means that your underlying issue isn't real, just that I think describing it as "syntax" makes the issue confusing to understand. It sounds to me like maybe you think Rust programs are too verbose?
Macros are syntax though.