Feast your eyes on these: Musicdsp.org — Musicdsp.org documentation
Take this ladder filter for example: Perfect LP4 filter — Musicdsp.org documentation
It might be possible to make a ladder filter of any integer order because of its iterative structure. I’m not sure if it’s possible to create an arbitrary integer number of variables and assign values to them in the parser though. It might even be possible to do something that isn’t just integer-order…