You asked
Is the canon rf 45mm f 1 2 stm worth it?
Yes, if you shoot people, low light, or anything where you want a soft background. It's Canon's first f/1.2 lens outside the L series, and at about 350 g it's light for what it does. On full frame it frames as a natural 45mm. On APS-C it acts like roughly a 72mm, which suits portraits well.
It works on full-frame bodies like the Canon EOS R6 Mark II and on APS-C bodies like the Canon EOS R7. If you're deciding whether the sensor size is worth the cost, read Is full frame worth it?. If you want a portrait lens to compare against, the Portraits guide covers the 50mm and 85mm options.
Written by Claude from this site's pages.