The librsvg package does not include rsvg-convert. It's also deprecated, and there's a note in the tar for Solus's version recommending newer versions.
rsvg-convert was needed to run oomix (not in the repo). There's a manpage for it but no binary.
Deprecation note is as follows:
LIBRSVG 2.40.X IS DEPRECATED!
You are looking at the 2.40.x series in librsvg, which is implemented
in the C programming language. This release series is no longer
As of December 2017, we are in the process of porting the internals of
librsvg from C to Rust. The public Application Programming Interface
(API) and Application Binary Interface (ABI) of librsvg remain
identical in the Rust version: it is a drop-in replacement for the
version you are looking at.
We strongly recommend that you update to the new version of librsvg,
as it has security fixes, lots of bug fixes, and ongoing development.
From the outside, the only difference is that librsvg is now much more
trustworthy when run against untrusted SVG files.