Sony is on a roll – the Xperia X Performance is the latest in its lineup to get updated to Android 8.0 Oreo. This comes shortly after the XZ and Xzs and the XA1 series updates.
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.