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 receive an automatic software update
Get notified about firmware updates, products alerts and more with the Support By Sony app.