@Sejal Kharbanda It depends on the communication during the PIP.
Usually, while the improvement parameters are laid down for PIP, the communication also includes that if the employee is unable to improve as per the plan/expectation, a date will be their exit date. In this case, no notice period or notice pay is required.
In a situation where the exit clause has not been communicated in writing during the PIP plan to the employee, notice period days are to served and paid or salary in lieu of notice period.
In addition to above, instead of termination, resignation is a better option. It will help the employee find another job and less audit questions in terms of termination documentation.
I hope the above mentioned is helpful.