Introduction Etiquette : Don’t ask « What do you do? » to someone you are meeting for the first (or even second time).
It is considered gauche and intrusive to ask someone what they do for a living, especially in higher society when people might not be “working”.
Usually, it’s good practice to be patient and as the conversation unfolds it’ll usually reveal what line of work your interlocutor is in.
If you really have to ask, opt for « What industry are you in? » which is always more appropriate