I use these operations on a daily basis, not in interviews. If you're ingesting third party data somehow (even if it's structured like JSON or XML) there are going to be cases where you need to hand roll a simple parser.
I’m genuinely very interested in the kind of data you’re dealing with. It’s common to need to reorder a list of strings, but I’ve personally never had any use case that requires me to reverse or sort _characters in a string_ to consume any kind of data (some kind of decoding, perhaps, but those tend to work better implemented at the byte array level, not string).
One thing to note: aside from programming interviews, these operations are fairly rare. And that's a good thing, because none of these produce results that are very intuitive, because they are not very well defined on strings in general (I don't fault Swift for this, but it's just a general problem with text). Using any of these to create a new String may cause entirely new characters to show up, or the length of the text to change. So Swift actually doesn't expose these as "string" operations, but operations on the characters themselves; in each case returning a new collection of characters that is not a String. Now, you can reconstitute them into a String pretty easily, but you should keep the this in mind when doing so.