In general, people who are confident in themselves take an outward action, such as actively talking to the first person they meet.
This time, I will introduce research that will help you gain confidence.
Moving Closer to Reach the Top: Approach Behavior Increases One's Sense of Power
According to this paper, self-confidence will begin to be exhausted automatically just by approaching the opponent forcibly.
Moreover, even if you don't actually get close to the opponent, you can get this effect just by floating the image of approaching the opponent in your head.
In other words, you can gain confidence by just approaching the other party.
This is a technique that even shy people can use.
There have been many research results recently that people can change their personality through behavior, but I learned that it is effective only with images without actually acting.
However, it is more effective to act than to imagine.
So I think it would be better to start with an image and then be able to actually act.