Yes. Don’t touch it. stateVersion has absolutely nothing to do with the NixOS version. The numbers mean completely different things, even if they look the same. No, really, see here.
@waffle8946 is talking about the version of the nixpkgs repository the software running on your machine was built from. Since the latest version of nixos-option supports this, and is only available on master, this either means you’re running nixpkgs stable, or have not updated your system in a very long time.
Make sure you update with nix flake update and not nixos-rebuild --upgrade, sudo nix-channel --update or whatever.