Why does my MacBookPro (model10,2) not update beyond macOS 10.15.17?

A MacBook Pro 10,2 cannot be upgraded beyond macOS 10.15.7.

See the following from Identify your MacBook Pro model - Apple Support

MacBook Pro (Retina, 13-inch, Early 2013)

Model Identifier: MacBookPro10,2

Part Numbers: MD212xx/A, ME662xx/A

Newest compatible operating system: macOS Catalina

To upgrade Safari from Safari 15.6.1 to a later version you would need to upgrade your Mac from macOS 10.15.7 to a later version and that isn't possible with that MacBook Pro

Since you cannot upgrade it to install Safari 16 or later, you may want to use a 3rd party internet browser that supports running their current version on your Mac. One option is Chrome: https://www.google.com/chrome/

Chase Bank is the only major financial institution using the outdated and privacy-intrusive "user agent" query to determine browser compliance. They need to abandon that practice. Unfortunately, that leaves you out in the cold until they realize the error of their ways and correct it.

The workaround for end users who are unable to update their Macs to a newer macOS version is to use a different browser.

Consider Brave:

https://brave.com/

Firefox is a distant second choice:

https://www.mozilla.org/en-US/firefox/new/

The bottom line is that there is nothing wrong with your Mac's version of Safari, but that bank is using an outdated and ill-conceived method of determining browser requirements. If you are so motivated direct their attention to the WWW publication User-Agent Client Hints (courtesy VikingOSX).

In-depth background discussion here: chase wants me to update safari to 16, should I do that? - Apple Community