Update: Both single SIM and dual SIM variants - with model number F8131 and F8132, respectively - are getting the update. Android security patch for November is included as well.
Original story follows:
You can head to the About screen of your phone to check if the update is available. It may not be as it just started rolling out and likely does not cover all regions yet.
The Sony Xperia X Performance originally launched in February last year with Android 6.0 Marshmallow and and was updated to 7.1 Nougat in November the same year.