Stop pop up ads

[S9PlusOwner1]

I have only had my S9 Plus for a month and I'm already starting to receive pop up ads. I have not installed any malicious apps and I scan my phone regularly. How to I stop these? I really don't want to factory reset my phone and have to reinstall everything I have (which isn't much but still) if I can avoid it. This is why I was weary about switching back to android after having iPhone for so long. 

[Aakashgv]

The app doesn't have to be malicious for it to push ads and notifications, tbh.

[S9PlusOwner1]

Is there any way of finding out which app or apps are pushing ads?

[Salimapur]

Tap and hold on notification and you will find out which app creating ads

[Raheel]

go to settings and disable pop ups

[Sahaxp]

You will only help a general reset. And do not install everything in the phone