What going through US Customs and Border Protection like?

I'll be heading over to the states from Australia soon and I feel very anxious about going through customs. I don't have anything to hide or anything that would be a problem for me. But I know things aren't great there right now, and I am visibly not white (Asian and Hispanic). I think i'll mostly be okay, but I'd just like to hear a recount of the process by someone who's experienced it. Particularly if you don't get allowed in? Do they just turn you around or would they move you to a detention centre? Please just any details possible i'd love to hear