Information about the availability of firmware / software updates can be found under Downloads section of your TV model support page
If a firmware / software update is available, there will be steps on how to install the firmware / software for your product and also instructions on how to check the firmware / software version.
If you cannot find a firmware / software update listed under the Downloads section, it just means that Sony is currently not offering a newer firmware.
You can turn on the Automatic Software Update option on your TV to keep your TV firmware/software updated to the most current version by referring to How to perform a software update
Get notified about firmware updates, products alerts and more with the Support By Sony app.