Location as a drop menu

As the location is a free text input, that wouldn’t be ideal for a dropdown. You could of course customise the job_filter template and list your regions/locations manually in a select box.

https://wpjobmanager.com/document/template-overrides/

An alternative could be suggestions so users can type a location and have it completed, using https://tinygiantstudios.co.uk/product/auto-location/