Of course Canon will introduce a couple "crop only" lenses to complement whatever APS-C RF camera they launch.
However, they will not be "RF-S" lenses. Canon has emphatically stated "there will be no EF-S lenses in the RF mount". But I think people have misinterpreted this.
It does not mean that all RF lenses will be full frame designs. Even so, of necessity there will be some "crop only" designs. But there will not be a specialized version of the RF bayonet mount designed to prevent those lenses from being used on the full frame mirrorless cameras, the way the EF-S mount does with full frame DSLRs. (A clue to this is that R-series cameras are able to use crop lenses now and shoot in a "crop mode", using only part of their sensor. This wasn't an option with Canon full frame DSLRs. But it has been a widely available feature on full frame/FX Nikon and others.)
There is no longer any need for anything like the EF-S mount. Keep in mind that when it was introduced in 2004 Canon was the only camera company offering both full frame and APS-C cameras... so in part the EF-S mount was created to prevent accidental use of the lenses on the full frame cameras. This was both to prevent user confusion and because Canon anticipated some crop specific lens designs might physically interfere the moving mirror inside a full frame DSLR. Since today's camera buyers are much more knowledgeable about the different sensor formats and lenses needed to accommodate them, because other camera and lens makers have not bothered to make a restrictive mount for their crop designs, and because the R-series are mirrorless... there no longer is need for a special mount like the EF-S.
There are rumors of some other crop only RF lenses, but primarily there need to be a general purpose "kit" lens (18-45mm) and an ultrawide (10-24mm). Both of these lenses have been on Canon's RF lens roadmap for some years now.
Full frame capable lenses lenses can serve most other purposes on an APS-C R-series camera. So why create any crop only lenses at all? Well, some reasons are that the lenses can be smaller, lighter and less expensive. They don't need to produce as large an image circle, so can use smaller diameter elements. Also, what's very wide on full frame is only marginally wide on APS-C... so there's a strong argument for a crop only ultrawide.
Ultimately there may be a few additional crop only RF lenses, such as a compact/affordable telephoto zoom, a more premium walkaround lens, possibly a compact/affordable macro lens and possibly one or two ultracompact/"pancake" lenses. This is much like what we see now with EF-S lenses.