In my day there were night classes, remember doing three in a row, 6 weeks, 6 weeks, 12 weeks, pat testing, 16th edition as it was then, and the C&G 2391 inspection and testing, also did confined spaces, cherry pickers, PLC's, and finally a degree.
However, in my day domestic was called house bashing, and there was very little specialist work connected to domestic, today that is no longer the case, solar panels, EV charging points, and more require special training, but I never even planned to be an electrician to start with, it was just how jobs took me.
My break was when SLD pumps wanted someone who could repair portable traffic lights, and I had that skill, so they re-trained me as an electrician working on pumps, and a spell in Algeria widened my experience.
So it is mainly down to the job you get, as to what you learn, no good learning how to repair a tunnel boring machine if you're never likely to even see one.
There was no Part P or scheme membership when I started, and I would move domestic, industrial, chemical, shop fitting, even ship building, what ever paid best at the time. And often the firms I was working for would send me on courses, it was a case of have bag will travel, Falklands, Hong Kong, even Scotland and Belfast, and Sizewell 'B' so many specials, 200 ton straddle carrier on the 7 bridge for example.
I had to taylor my CV, to suit job applied for, as no one would believe I had worked on so much. It seemed I was jack of all, and master of non, if I listed it all.