With this we can see tachnically speaking, is not difficult to change any already written parameter - to change the code value of it, when talking about crypto-currencies the difficulty only comes when adding non-existant features. You can modify any of those features here https://github.com/bitcoin/bitcoin/blob/master/src/init.cpp

But you can't just alter some value in the code and get with it, consensus should be reached to modify even the minimal thing on Bitcoin as you'll modify the code in thousands or millions of user computers, it's decentralized.