Not having to wait 55 minutes if you ever miss a train, or hoping a theoretical 15 minutes for a bus with a very high chance of skipping runs or breaking down. And a system to actually be where you want to be, instead of then having to walk multiple kilometers after reaching the central station.
A lot more public transportation ( tram, bus, brt, subway, depending on the budget), mixed zoning, pedestrian zones/streets, proper bike lanes, expensive parking inside the city, bike lease (like Vélib’in Paris), trains to facilitate transit between zones without good public transportation access (like suburbs or countryside) and city center.
Sorry, more public transport works only to an extent, many examples over the world. Germany, for example, makes it kinda hard and hurtfully expensive to even get a driver’s license. Above 2000 Euro and at least a year in the cities. Many just give up. But that’s not the way either. I for myself would simply forbid large SUV and other large vehicles in any denser populated areas, massively support the hydrogen and fuel cell technology, stop listening to the greedy mofos who tell everyone electric cars are the future, they are not in the current state of development, only for short distance deliveries. Movement of any goods on rails, small (electric, hydrogen) vehicles to the shops. More space for bicycles is a way, but it works only to an extent, too.