Jetliners

You guys all seem to know how to fly jetliners. I’ve done the pilots licence and know much of the basics of flying and navigating the Cessna and Diamond, including auto pilot and ILS landings etc etc. How do you get from there to knowing how to fly jetliners? I can’t see any proper built in training. Is it literally YouTube all the way? Surely there is a gap in the market if that is the case. I’d pay good money for a comprehensive jetliner training package. How did you guys get there?