Is it possible to increase or decrease the pressure? What should be done for this?

You can decrease or increase the pressure.
In order to reduce the pressure, it is necessary to reduce the force or increase the area of ​​its application.
In order to increase the pressure, you need to increase the force or decrease the area of ​​its application.
For example, if you put thin wheels on a large machine (tractor, Kamaz), then it will leave very deep ruts after itself and ultimately will not go far, since the pressure on the wheels will be too great. In order to reduce the pressure, the application area is increased, and it is precisely in such machines that large and wide wheels are made. Or you have to lighten the body, and therefore reduce the force.