How can I use Methods in digitalWrite(): digitalWrite(int, "methodHere")?
In this situation it is far more efficient to use #define and conditional compilation.

// Uncomment this for tinkercad
// #define INVERTED

#ifdef INVERTED
#  define ON HIGH
#  define OFF LOW
#else
#  define ON LOW
#  define OFF HIGH
#endif


Then just use ON or OFF in place of HIGH and LOW.

digitalWrite(3, ON);


But the reason you have a problem is not because you are trying to use a function as the value to digtalWrite() - the problem is actually in your basic C syntax.

You are using the assignment operator (=) when you should be using the comparison operator (==). For example here:

if(highOrLow = 0)


you should have:

if(highOrLow == 0)