mac is updated to 13.0 but Safari is at 5.6.40 and how to update Safari?

Safari gets updated with the OS. Where did you read the version number? Was it in about Safari from the app or was it from a website?

macOS lies to the world about what version of OS and Safari is reported in the HTTP protocol.

To better understand your question, can you provide the following version numbers?

• Click on the Apple menu in the upper left corner, and choose About This Mac. Let us know what Mac OS you're running. (Asking because you've listed a MacBook Pro 17" in the description).
• In Safari, click on Safari in the menu at the top, and choose About Safari. This will show what version of Safari you have.

As was mentioned below, Safari is typically updated with a MacOS update...it's not normally done separately.

Hope this helps.