The process will still void the warranty of the device
Simply open the dialer, enter *#*#7378423#*#*, and then tap Service info > Configuration > Rooting Status. The “Bootloader unlock allowed” status should be “Yes.”
All the specific info on the matter can be found on this page on Sony’s website. Users with supported devices interested in unlocking them should read and follow the instructions there to get through the process.
Sony asks for a valid email address and the first 14 digits of the MEID number (enter *#06# on your phone to view it). The process will void the warranty of the device.