Safari

Safari is upgraded when you upgrade macOS on your Mac.

If your Mac mini is a 2018 or later (from Apple menu > About This Mac) see the following for instructions for upgrading to Venture: How to upgrade to macOS Ventura - Apple Support

If your Mini is running Big Sur or Monterey and can't be upgraded, there is a Safari security update to 16.2. See: Apple security updates - Apple Support and Keep your Mac up to date - Apple Support

If it isn't possible to upgrade to at least Big Sur or Monterey so that you can get the current version of Safari, I would recommend using a 3rd party browser that supports it's current version on the macOS that you have. One option is Chrome; the current version of Chrome will run on macOS 10.13.6 or later. https://www.google.com/chrome/

See the "Export a bookmarks file" section of Import bookmarks, history, and passwords in Safari on Mac - Apple Support

Version 16.2 (18614.3.7.1.5)

....