Only an operating system upgrade from your present El Capitan will update the Photos application.
From your menu > About This Mac, note what is in parenthesis on the Mac product description line, and then using only Safari browser, check your hardware compatibility in How to get old versions of macOS. That will indicate which release of macOS you can upgrade too.
Should you choose to upgrade, and certainly before you do, back up your El Capitan with Time Machine, and check your printer/scanner/software vendors for product support of the newer operating system.