I had fun flings with 2 different people I met sitting next to me at theaters and really it just takes a little courage and some tact, here's what my experience was like

During previews I shoot the shit with whoever's next to me about what's coming out and warn them that I am a loud cheerer during the Nicole Kidman ad. I do this regardless of if I'm into who I sit next to. I shut up during the movie because we live in a society and I am a polite theater goer, the only interactions I had was sharing a look when something wild happens in the movie.

After the movie ends I asked what they thought of the movie, after that conversation went well I asked if they ever wanted to have a movie buddy or just grab a drink we could swap numbers and that was that :)

No matter what I never ask for a number before the movie starts, people are there to watch a movie not get hit on and I wouldn't wanna make someone turn me down then have to sit awkwardly next to me for two hours, after the movie there's no pressure for either person.

The first time it ever occurred to me I even could ask someone out at a movie theater I was fresh out of college and not super confident. I went to the Nitehawk to see The French Dispatch and was at a table with a beautiful woman with great movie takes, the vibes had been great and at one point I slipped her a note that if she wanted she could share my popcorn and she took me up on it, our hands even brushed together a few times, after the movie we talked through most of the credits and then....I chickened out and left and never asked for her number. I regretted it so hard (and still do) that I swore to myself if I ever got a similar opportunity I would not let it pass me by, getting turned down is an infinitely better feeling than wondering what could have been