How would a receptionist working at the front desk of an office tell another co-worker that a visitor has arrived for a meeting? Ex. - 'Good morning. Mr. Smith is here for an appointment with you and is ready to be picked up.' or something along those lines.

Question

Answer

If the visitor is unexpected:

Sir/ Ma'am, there's a Mr./Mrs./Ms./Miss (last name) here to see you.

If the visitor is expected:

Sir/ Ma'am, Mr./Mrs./Ms./Miss (last name) is here.

Answer

Mr Smith is here for his meeting/appointment with you and is waiting in (where they are - for example reception or the meeting room)

You don’t need to say they need to be picked up, that’s obvious.

Answer

Don't say "another co-worker". You can say either "a co-worker" or "another worker". When you say "another co-worker", "another" is redundant.