Quick electrical equations question in regrads to RMS voltage.

Hi I’m having a bit of trouble using the P=VI formula. I want to work out the watts and I’m given voltage in RMS, and I can’t remember whether I have to change that voltage to 0-peak before I use P=VI.

Your help will be appreciated.

No.
Don't change it. RMS is used to enable the P = VI equation to work for AC as well as DC