Mine started playing out around 7/8 years old, directly outside the house, with me watching them (quiet unmade up no through road, only cars for access, going v slow due to unmade up nature of road). They typically played football, skipped, rode bikes up and down road etc. The advantage of being in the road rather than in the garden is that other children joined in - football in a group is far more fun than kicking a ball around by yourself - as is skipping etc.
As they've got older, they now walk to the shops unsupervised, go to the park for a picnic/to play football/walk (approx 1 mile) to the leisure centre to go swimming.
They're now early teens, and no vandalism or anti-social behaviour etc. On the contrary, they're well adjusted mature children, with good social skills and a huge support network of local friends in addition to their school friends. They seem less social media reliant than those who didn't play out, and more outdoorsy and more aware of others around them, helping out younger children etc.
Obviously, we didn't just open the door aged 7 and boot them out with no supervision. We gradually built up to more and more unsupervised play. I honestly think it's been really good for them, and helped them mature and develop social skills.