I have MacOS High Sierra 10.13.6 It says no updates available Should I update my OS?

You need a 2012 or later Mac to upgrade beyond High Sierra.

See: How to get old versions of macOS - Apple Support

From my understanding on MacOS you just ned a more up to date Browser than Safari...

Might try this, it's Chrome Browser without google & without Ads...

https://brave.com/

The security update is for Monterey so I wouldn't worry.