How do I determine which OS upgrade is compatible for my MacBook Pro?

The model year of a MacBook Pro is available at Apple menu > About This Mac.

An Early 2008 through mid 2009 MacBook Pro can be upgraded to El Capitan 10.11.6  but no later version. See: How to get old versions of macOS - Apple Support

A mid 2010 through late 2011 MacBook Pro can be upgraded to High Sierra 10.13.6 but no later version. See: How to get old versions of macOS - Apple Support

A mid 2012 through early 2013 MacBook Pro can be upgraded to Catalina 10.15.7 but no later. See: How to get old versions of macOS - Apple Support

A late 2013 and mid 2014 can be upgraded to the latest  version of Big Sur macOS 11 but no later. See:How to get old versions of macOS - Apple Support

An early 2015 or later can be upgraded to the current version of Monterey macOS 12. See: How to upgrade to macOS Monterey - Apple Support

You can also use this article to see which versions of macOS are compatible with various Apple hardware:

https://eshop.macsales.com/guides/Mac_OS_X_Compatibility

Just because the OS is compatible with the hardware does not always mean the computer meets all the recommended specifications for memory or adequate free storage. Usually searching online for "macOS xxxxx requirements" where "xxxxx" is the actual OS name will get you an Apple article for the technical requirements for that version of macOS. For example searching for "macOS mojave requirements" gave me the fist link for the Apple website for "macOS Mojave - Technical Specifications - Apple Support" which provides information for the minimum amount of RAM and free storage space needed for the install.