Yeah not every city needs a Central Park size green space nor do people need lawns for everyone. Trees along the sidewalks, hedges in front of buildings… Look at the rich part of your nearest city. It’s probably fairly dense except for its park, but it’ll be shaded and have room for people to grow some plants on their porch or in front of it or somewhere like that. Space that would otherwise be bare concrete.
There’s also rooftop gardens but that’s a whole other thing.