Hi,
Is it possible to edit PLECS RT box inbuilt library blocks like PWMout and PWMcapture? If I change inside the schemtic of the block, will it reflect in the code generation?
You can break the library link by right clicking the component and selecting Subsystem + Break library link and then right-click + Subsystem + Unprotect.
However, these changes will only impact the offline simulation and have no bearing on the generated code. The offline simulation models were created to reflect the behavior of the RT Box, so these modifications will likely make your offline simulation models less representative of the hardware.