There are ppx things that can automatically derive "to string" functions, but it's a bit of effort to set up, it's not as nice to use as what's available in Rust, and it can't handle things like Set and Map types without extra work, e.g. [1] (from 2021 so situation may have changed).
Compare to golang, where you can just use "%v" and related format strings to print nearly anything with zero effort.
[1] https://discuss.ocaml.org/t/ppx-deriving-implementation-for-...