How are the SAP Project in PWC India? Is going to office necessary in PWC India?

Okay. Could you please tell me what's the average pay for 4 yoe sap sd ?

Depends on your role in the project & also the type of project you get allocated to.

Certain roles involve frequent travel from client location & working from there.
Whereas in other cases, you can work from home.

As such, there is no official WFO mandate, however local leadership can ask based upon the project requirements.