Pop up says iPhone is infected with 19 viruses

So..I was on this website and an add popped up on my screen, as they always do. I accidentally clicked on it by mistake (as it covered like half the screen) and then a whole new tab opens up on Safari and there is a pop up on it. The pop up has the Settings App icon in one of the corners and it had a message beside it that states ‘your iPhone has been infected with 19 viruses. Please click ok to continue’ or something of that nature. The pop up had no ‘ok’ button, just a ‘close’ button. Unfortunately, I panicked. I hit the ‘close’ button, deleted my history, closed the app completely, and cleared Safaris history in settings. I was just wondering if this was a scam or actually legit? And if it is real, how can I get rid of it?