Is is this a scam or a legit warning?

I was browsing safari and suddenly I was brought to a website with apple security In the top, the message said

” your iPhone has been infected with the Trojan virus, if you do not take these proper steps then your data could be sold to third parties.”

When I clicked on fix this it brought me to the App Store to some random app. Is is this a scam or a legit warning?

[Re-Titled by Moderator]