You can never tell. If a site you normally go to gets hacked, it can be sending out malware when you connect to it. (It's happened many, many times.) And most anti-virus apps and anti-malware apps don't take up much space or CPU time, so it doesn't hurt to be save rather than sorry. (We see so many questions of the form of "now that I've gotten this virus ...". Have something good installed and you won't even know you got it.)
I just got a S8+ and was wondering if adding Lookout Security is advised?
Thanks in advance