The tour is the sale and it is usually improvised
Somebody who walks in has already decided to consider you, and what happens in the next fifteen minutes decides the rest.
A prospective member arriving in person is at the highest intent they will ever be. They are also frequently uncomfortable, because they are standing in a room full of people doing something they are not sure they can do.
Most tours are handed to whoever is free, follow no structure, and consist of walking past equipment while describing it.
What works better is a conversation before a walk. What they want, what they have tried, what they are worried about, and then showing the parts of the facility that answer those things specifically.
The moment that matters most is usually addressing the discomfort directly. Somebody told plainly that most new members feel out of place for a fortnight, and shown what the quiet hours look like, relaxes visibly.
Measure it. Tours given against memberships sold is a number most gyms could produce and do not, and it varies enormously between the people giving them.