You asked
Is the canon rf 16mm f 2 8 stm good for landscape?
Yes, it's a sensible choice for landscape, with one caveat. On full frame, 16mm is a genuinely wide view, which suits big skies and strong foregrounds. The landscape guide says you'll usually shoot between f/8 and f/11 anyway, so f/2.8 is more speed than you need. The lens is lighter and cheaper than the f/2.8 zooms, and it has no stabilisation. That matters little on a tripod, which most landscape work uses.
On an APS-C body it frames like 26mm, which is much less wide, so pair it with a full frame camera such as the Canon EOS R6 Mark II. If you want a zoom to cover more range, the guide also suggests a wide zoom around 16-35mm.
Written by Claude from this site's pages.