Will a led light be able to be turned on and off from the transmitter if I don’t have a receiver switch?

Unless the RX has that capability built in then no. I can't think of any RX that has that feature built in at the moment, I don't really recall any brand being able to do this. You can actually use an old servo to work as an LED switcher or even one one of those real cheap 9G servos used in foamies, just have to watch the amp draw with those. I've purchased prewired switchers as cheap as $1.80 from China that are plug and play, just have to wait a few weeks to get them. You have plenty of options.