http://www.xperiablog.net/2018/02/15/only-xperia-xa1-family-supports-night-mode-option-will-lose-it-in-oreo-update/
It may not be widely known, but Sony does have an option on the Xperia XA1 family of phones (Xperia XA1, XA1 Ultra and XA1 Plus) to reduce the blue light, through the “Good night actions” function in the Xperia Actions feature. This is not as fully featured as the previous ‘Night Light’ mode, but it’s helpful nonetheless.
Well Sony Mobile has confirmed that this feature will not roll out to any other Xperia smartphones. Even worse, Xperia XA1 owners will lose this feature when they upgrade from Android Nougat to Android Oreo. We have no idea why Sony would remove the feature, but maybe it wants to make the software experience consistent across devices. Or, Sony could just add it for everyone…
The Xperia XA1 family supports reducing blue light through Xperia Actions
Sony confirms that this feature will be taken away in the Android Oreo update