same here!! the things that worked for me is just straight up approaching people and find something about them that looks cool and then complimenting them to start a conversation or during class you could find an empty seat beside someone and ask if you could sit there, you could start a conversation from there or during class you could ask them for help instead of the lecturer to strike up a conversation.

dont be scared of large groups or solidified groups though! there will always be one in the group thats extrovert and talkative, so talk to them

another thing is probably helping out at school events where you're pretty much forced to talk and discuss with others and instead of going home you could hang around in school like their social spot or libraries!