It's a weird and tricky balance that one has to strike, in the US, in 2021 ...
On the one hand, I feel strongly that kids should have free time and energy to explore and experiment and I am reinforced daily in my instinct that a "bored" kid is just another 10 minutes away from doing something interesting and magical.
On the other hand, as my oldest children reach pre-teen age, and I pay more attention to their pre-teen peers, I find myself agreeing with the "idle hands are the devils playground" heuristic. I want my teenage children busy doing constructive and healthy things.
But it gets complicated ... you can't just plug your kid onto a age 12 or age 13 baseball or hockey team. Those kids have been playing the sport (and playing the sport together) since they were 4 or 5. Your kid will not make the team or will be conspicuously out of place. So if you've been free-ranging it for their first ten years you're going to need to get more creative as you transition to the teenage years...
I have seen things like mountain biking and BJJ be good options...