hey there! i wanna update my mac to latest version but i didn't find software update option

Once you have the (Year model) information from the menu > About This Mac panel's product description entry, you can compare that to the hardware requirements at How to get old versions of macOS - Apple Support to determine which operating system you can upgrade too.

You want to perform a Time Machine backup before any upgrade of the operating system, and also check if your printer/scanner vendor offers drivers for that operating system choice. Also, it would be wise to check if your third-party application vendors offer versions compatible with the intended operating system upgrade.

The Age of this computer will Govern what newer version of macOS it will Qualify to install. Use About this Mac from the Apple Icon on Desktop - the required Information will be there.

With the above information in-hand - follow this How to get old versions of macOS and verify what version this computer Qualifies to install.  For Best results use Safari to commence the download as Others may not work.

Safari will open a redirect and open the Apple Store where the download can commence.

Tips Monterey Upgrade Latest version of macOS

Tips Big Sir Upgrade Released 2020

macOS Catalina 10.15 hardware requirements Released 2019

macOS Mojave 10.14 hardware requirements Released 2018