Not sure if this is the right way to get help but yesterday evening got mssg in my iPhone settings that my iPhone is severely damaged by 13 viruses!What to do ?

Got yesterday evening mssg in settings from my iPhone that my phone was severely damaged by 13 viruses and that I have to do something immediately!

Got instructions and to install some app that will protect my phone .

Need a help since never before got such mssg and not sure if it’s phishing or really have to do something ?

Thank you for your help