I'll take a stab, since I'm here, but I'll admit, I'm relatively inexperienced on the world scene.
The U-23 world team trials that you are hearing about right now are United States trials to determine which U.S. wrestlers will represent the U.S. at the U-23 World Championships to be held in November in Poland. The U-23 stands for under 23, but the actual age constraints are 19-23, with exceptions for 18 year-olds who can get in, if their doctor and their mother sign waivers.
U-23 is a new wrestling classification. Before now, you would typically hear about the Junior World Championships (U-20) and the Senior World Championships. For each of those, there is also a U.S. team trial to determine the wrestlers who will represent the U.S.
Finally, there are a host of qualifying criteria that can be met in order to be allowed to enter the trial tournaments. For instance, Top 6 from Fargo, NCAA D1 All-American, Previous Junior World Team member, are just some of the qualifying criteria.
All of this and more can be found at
https://www.teamusa.org/USA-Wrestling.
