Not the trains i usually go on
First great western have 3 Pin UK sockets under the seats and also USB sockets (although i cant remember what type of USB they have, as usually i just plug my UK plug in) . Although granted you wouldnt be able to get that on airlines.
Its annoying as on aircraft they "assume" that the one end of the cable that usually plugs in to your 3 pin plug is type USB-A and the other end which goes in to your device is the spepcific type (be it iphone type or USB C)
However on my charger the end that goes in to my UK plug and the end that goes in to my device is USB-C at both ends.