How it works depends on the aircraft. In some the only centering force is the airflow over the rudder. So no airflow they Flop left or right freely.
On other aircraft there is a bungee system to center the rudder.
The amount of force needed depends on many things….not least of which is the size and speed of the aircraft.
Then there is the linkeage between pedals and rudder….also very different setups in different aircraft.
In some the rudder was linked to the aileron to ease workload of the pilot.
And lastly there are different types of control boost.
The rudder in a C-150/152 is very light at almost any speed and easy to overcontrol for a newbie pilot.
The C-210s I flew required relatively strong forces at any speed but that was one of the bungee systems I believe. But the rudder trim on the bigger Cessna aircraft is easy to use and makes it almost as often used as horizontal trim.
Our Saratoga definitely had some form of bungee system to center the rudder and give a slightly heavier feel than you would have without it. But that also made it less likely to overcorrect and swing the tail around….with the long fuselage compared to the smaller Cherokee types the third row passengers appreciate that I think. The trim knob on the Saratoga was the only thing I never grew to like in almost 1000h flying that airplane. Location and use just far inferior to that of a Cessna or Beech.