Unfortunately, it is not supported to only display list-entries that is most close-by or relevant to the visitor at the moment. We do apologize for the inconvenience.
With that said, we recommend enabling the store locator “Hide all markers until a search is done” option by navigating to Maps -> Edit -> Store Locator -> Ensure that you have enabled the Store Locator -> Scroll down to “Hide all markers until a search is done” -> Please enable this option.
The markers listing will be hidden until a visitor search for a marker and will then only display the markers within the searched radius.
Alternatively, you can change the number of items to be displayed on a page by navigating to Maps -> Settings -> Marker Listing -> Scroll down to “Show X items by default”.
I hope this helps clarify, and I look forward to hearing back from you.