You asked
Is the fujifilm xf 400mm f 4 5 r lm ois wr good for sports?
Yes, for wildlife and sport the 400mm f/4.5 is a strong choice. It's a stabilised, autofocus super-telephoto prime, and on Fujifilm X bodies it frames like about 600mm on full frame. That's the reach that wildlife and sport photography usually needs. It's a specialist lens, though, so think about whether you'll really use that much reach.
If you want faster light for sport from the sideline, the Fujifilm XF 200mm f/2 is a fast telephoto prime built for that job. For more flexibility and less commitment, the Fujifilm XF 100-400mm f/4.5-5.6 covers a wide range of subjects. Long lenses hold their value, so buying used can save you a lot.
Written by Claude from this site's pages.