Is it ok to factory reset a iPhone?

If there was any kind of malware or malicious code/virus on my iOS device, would the Reset and Erase All Settings take care of it? Nothing was really done at all to make me think there would be any such kind of thing on my iPad (4th gen), however I went to a super old e-mail that that had spam etc. in it (done with that e-mail permanently now), so just incase that was an issue, would that get rid of any kind of malicious code? I have also read so many guides including this: https://techtade.com/factory-reset-iphone/ But after all these question I have one more quick question that is Is it ok to factory reset a iphone?