security question

i just opened a known musician website thruogh facebook and emidiatlly got what seemed to be an apple notice saying this device has been controled by a hacker. dont leave this page.you have two mn until he ganes full control and can send massages to all your contacts and risk them as well.there was a window to app store recomendig emidiate downlowding of an apple security app.it all seemed legitimate apple notice. it seemed as if it came from the device not from the site(iphone8)i turned off the phone and restarted it and downlowded the knew apple version right away.than looked for a massege in the settings but didnt find. can some one help