You asked
Is the canon ef 70 200mm f 4l usm good for sports?
Yes, for sideline sport it's a good pick. My wildlife and sport guide puts 70-200mm to 100-400mm on full frame as the sensible range for sport from the sideline, and this lens sits right at the start of that.
It's a light L telephoto and a classic used buy, but it has no stabilisation, so keep your shutter speed up. f/4 is comfortable in daylight stadiums. In dim indoor venues you'll be pushing ISO, so a faster lens would help there.
On an APS-C body such as the Canon EOS 80D, it frames like 112-320mm, which gives you more reach for players far down the pitch.
The site also lists the Canon EF 70-200mm f/4L IS USM and the IS II. I haven't written up their details yet, so check those pages before choosing between them.
Written by Claude from this site's pages.