The stiffness of boards, boots and bindings is all relative to a riders weight.
Freestyle riders normally go for softer setups so that they can get a lot of movement and so that they are more forgiving. This allows them to more easily ride park features and do lots of tricks like buttering, boning, grabs and so on.
So to answer your Q, you can still ride park but you just want to find gear that is somewhat flexible for you. If you are twice the weight of someone else, then your setup will need to be twice as stiff for it to react to your movements in the same way.
Have a look at some freestyle boards and look at each snowboards recommended rider weight range, then make sure you fall with in it. That is how companies design their boards.
As for boots and bindings, you'll just have to try them on.