I referee volleyball. Our instructions are to get the home team - preferably the athletic director or somebody similar but ultimately the home coach if there's no one else - to do something about somebody behaving in an unacceptable way.

We're advised not to act too friendly with coaches because some people might think we're favoring their team. Involving the coach if you don't have to might create the opposite impression, that you're upset with the coach or team.

I've never experienced or heard of this being an issue in volleyball. I'm sure it's happened, particularly at the club level where parents are paying big money for their kids to play. Other sports, particularly basketball or football, it definitely happens.

Came to say the same. Except it is the team captain that you should address.

Typically they will then escalate to the coach/club coordinator or something. By the time that is finished the guilty party has either left by their own volition already or through the other spectators.

Volleyball is a chill sport and I have had only once in refereeing junior games (<16/18) that a spectator went to far.

Most shenanigans if any is typically directed at the referees not even the players.

There has been a slight uptake in nastiness that I attribute to the sport becoming more popular.

(Context: the Netherlands, 12 years of experience from the lowest classes to 2nd division)