Sony Mobile released new firmware updates for the Xperia XA2 and L2 recently. The Xperia XA2 and XA2 Ultra saw an update that moved the build number from 50.1.A.4.76 to version 50.1.A.4.102. The update first was released a couple of weeks ago, and arrived with the 1 January 2018 Android security patch.
Sony also pushed a minor update for the Xperia L2 a little while back, which moved the build number from 49.0.A.2.62 to version 49.0.A.3.72. While Sony pushes timely updates for its flagship phones, it will be interesting to see how it will treat its 2018 mid-rangers, in terms of frequency of updates.
Xperia X Performance and XA released in the United States
New firmware 14.2.A.1.136 certified for Xperia Z1, Z Ultra and Z1 Compact
Xperia S/SL firmware build 6.2.B.1.96 gets certified [Update]
New firmware (6.1.G.0.0) certified for Xperia S; unlikely to be Jelly Bean