Is EF-S 18- 135mm enough for children's sports meeting?

Whether a lens with focal length is enough depends on your own judgment.

The same scene, shooting the same subject, because different photographers have different shooting purposes and shooting requirements, they will use lenses with different focal lengths.

If you shoot a children's sports meeting, if the shooting position is basically not limited-close-up shooting is allowed, and the lens of 18- 135mm is basically enough-no big close-ups are taken.

If the number of seats is limited-you are not allowed to get close to the lens, the lens of 18- 135mm will be a little difficult-the distance is far enough.

Also, if you want to take a big close-up, you'd better use a telephoto lens. If you want to take a very impactful photo, you'd better bring an ultra-wide head.

Off-topic: SLR is a interchangeable lens camera. Its biggest advantage is that it can change the lens-use different lenses according to different shooting needs. Why use one lens instead of multiple lenses?