honestly, for a man, a clean shirt, 2 buttons opened and jeans should be enough ... you just need to look ok/clean. Oh yeah, put away, in your pockets, the headphones, mobilephone or stop that smart watch, you're going to an interview to talk with someone about a job.
that's my opinion.
O yeah, maybe, just maybe, if you have those 10++ yrs of ex in the field ... you can go with that Metallica/Megadeath/ozzy orbourne tshirt and ripped jeans and uncut hair and beard... MAYBE