My 2017 iMac Retina 5k 27 inch needs a Safari update
what is the latest version of Safari that I can update to? I'm using macOS Ventura 13.7.1. Do I need to update that too?
iMac 27″ 5K, macOS 13.7
macOS Ventura is the last compatible os for a 2017 iMac. The last update for Ventura was 13.7.6.
Apple has Safari updates for the 3 most current macOS versions (Sequoia, Sonoma, and Ventura) so you can update Safari to the current Safari version 18.5.
To update both Ventura and Safari, see instructions in Update macOS on Mac - Apple Support