whilst i highly recommend making friends outside of your course anyway, it's also great to make friends on your course too.
Large classes can be intimidating but honestly the best way is to just start chatting to people. Talk to people as you're waiting for a lecture to start, whilst you're waiting, etc. It can just be small talk, and I highly recommend going up to people with some cool outfit or an accessory you like, or if they're wearing merch/band shirts you like and complimenting them on it! You gotta get the confidence to just start talking. People are either going to appreciate you talking to them, or be dismissive in which case oh well, you can move on and find someone else.
Getting your foot in the door is the first step. Make one or two casual acquaintances and then saying something like "oh does anyone want to make a study group/group chat" then everything will start falling into place.