Confidence!
Its really that simple, except it’s not otherwise everyone would have it! IMHO what you really need to do is break down the key parts of your problem.
Alcohol makes you confident and improves your self esteem. It also makes you less inhibited by social norms.
So thinking about that, you can take a few hints from it.
You can take each of these parts on their own. Boosting your self esteem could take many forms, having a career/job you’re very good at. Being good at your hobbies and feeling that you have agency in yourself.
Confidence in social situations takes time to cultivate. There’s nothing like just pushing yourself out there and talking to people, even girls. Just remember, getting a number doesn’t have to be the end goal - just existing and being chill with people as friends is a solid step on the way.
Being less worried about social norms is a part of confidence IMHO. Not taking yourself quite so seriously is important for me, realising that in reality, everyone has insecurities.
Personally, I would begin from the start, working on your self esteem so you feel valuable to a pretty girl as a possible partner. From there you can improve how you cope and interact on a social level before finally letting go of social worries like being rejected.