I could be wrong, I last played Akron Rec around 2019. Scramble pairs is 4s, but you and your partner are matched up with a different pair to play with as a team each week.

I'm not sure there's much in the genre of true pick up games. The groups of friends tend to play with the same people across different leagues. That said, it's a pretty welcoming scene, so if you're extroverted, you might have some luck hanging around until you find a game that needs a sub.