Is valid for FreeRtoS project to modify the port.c file? I’m using at the moment the PIC18F port. I’m asking that because I have developments that needs a different SW/HW config and the provided for the port assumes that I need to use Serial communication and the CCP1 for Tick generation. If I want to use as example Timer 0 for Tick generation and no serial com (e.g.:maybe I need the pins for other stuff) is licit to modify it? or there’s a way to get around it? Best Regards.

You have the source code so you can do as you wish.  Ideally the port layer would remain untouched, but this is not always realistic.  You could make prvSetupTimerInterrupt() a callback function into the application so the application decides how the tick is to be generated. Regards.