It's not a straightforward yes or no. Many factors come into play. The content, the art style, and the intended audience of the comic all determine if it's suitable for kids. Generally, comics with violence, complex adult emotions, or mature concepts could be too much for young ones.
It varies. Comics come in all kinds of genres and content. There are plenty of kid-friendly comics that focus on fun, adventure, and learning. But some adult-oriented comics could be too mature for children.