Edit: To add a bit of context here a lot of people are talking about pesticides and fertilizer and stuff like that but we don't do anything like that, we just mow it when it gets a bit long. Does that mean our lawn is technically a meadow?
A meadow, or natural lawn, or whatever you want to call it would be a mix of grass, clover, and other "weeds". It wouldn't require anywhere near as much chemical treatment (if any) and could be mowed and watered far less often. To me, it would also be allowed to grow long enough to flower, to promote pollinating insects.
I tend not to let the clover or dandelions flower though, as it attracts bees to the lawn, and barefoot children (very common in my country, and not looked down on like in the US) and bees on a lawn aren't a happy mix.
My garden is filled with heaps of flowering annuals and perennials though.
We do set rules, it's just that we don't always maintain them very strictly, and he loves to bend them. And when he does play outside to get more Minecraft time, he thinks 15 minutes outside it enough.
It seems he just has no idea what to do outside. As a kid, I regularly played outside, probably because I had to, and so did the other kids in the neighbourhood, so we played outside. But none of his friends plays outside, so there's nothing to do for him outside.
What doesn't help is that we live in a city: no backyard, no fields or forests behind the house, and watch when you cross the street. Plenty of playgrounds fortunately, but the youngest, who loves to play outside, is just 5, which is a bit young to be outside on his own, so he's learning to adapt to indoor play. Maybe playing outside is getting trained out of kids because of the environment we live in.
Regarding setting rules: Kids are very bright when it comes to getting their way. If there's any loopholes they'll exploit them. If they detect weakness in resolve then they'll push and push using negotiation, guilt, deception, etc... The question they're trying to figure out is, is my parent in charge or can I be? The hardest but best thing you can do as a parent to instill disciple is to be clear, consistent, and follow-through. It's really hard. I'm in the midst of it too!
In my limited experience (ex cub leader [mixed sex groups], church kids helper, worked with children for 15 years; kids and nieces/nephews of my own) most boys behaviour declines rapidly if you don't "run them", but most girls aren't affected in the same way.
On our scout camps (mixed sex, mixed age, for the last 20 years at least) in free time the girls _tend_ to retreat to their tents and chat and the boys _tend_ to hit the field and run around like idiots. There's obviously a lot of selection bias in these groups too, they do outdoor pursuits, rough camping, etc. -- these girls are fit and hardy and as capable at kayaking/hiking/climbing/backwoodsmanship as the boys (indeed at the top end, 14yo, the girls are often fitter and stronger as they tend to grow a little earlier than the boys do). There's probably some observer bias too, of course, and this is anecdotal (but longitudinal).
My observations of toddlers at "mums & toddlers" groups suggests the ones who run around with a pram are usually boys (though that's far from exclusive; and the mothers [it's about 1:30 men] have very strong gender bias, which might be the origin of that effect).
YMMV.
Interested in other observations, FWIW I'm in the UK.
https://www.nhs.uk/live-well/exercise/physical-activity-guid...
I always just took them as fun time and some kids took them as annoying burden that should be avoided. I not once thought about that they are necessary to develop my body and motor skills.
I always took Judo training as a near perfect way to improve my movement skills though.